Lecture: Update on Pediatric Ocular Biometry and IOL Power Calculations

The growing eyes of children necessitate tha pediatric ophthalmologists acquire sufficient knowledge of the basics of pediatric ocular biometry and IOL power calculations. The tools for calculation of keratometry, axial length and intraocular lens power are same as that of an adult eye but implantation of IOL in growing eyes needs under-correction and titration of IOL power.

This live webinar will focus on various methods of ultrasound and optical biometry, various methods of under-correction, IOL power calculation formulas, newer methods of biometry and choices of IOL in pediatric cataracts. A review of current tools and considerations for intraocular lens power prediction in infants and children will also be presented.

Lecturer: Dr. Neelam Pawar, Ophthalmologist from Aravind Eye Hospital in Tirunelveli, India


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DR. Pawar: Welcome to Cybersight Live Webinar. I’m Dr. Neelam Pawar from Aravind Eye Hospital, and I’m going to be talking about pediatric ocular biometry and IOL power calculations. I have no financial interests, and I would be happy to take any questions at the end of my presentation. So I will be discussing on various methods of ultrasound and optical biometry, and issues in pediatric cataracts. Here comes the poll question first. What is your position? Are you a pediatric ophthalmologist, comprehensive ophthalmologist, a fellow or resident, medical student, or biometrist? Let’s see how many people are with us today. Yeah, great to see that 50% of you are pediatric ophthalmologists, 25% are comprehensive ophthalmologists, and 15% are biometrists. Cataract surgery in adults has gone through a transformation in IOL calculation and power aspects, but pediatric cataract is still lagging in these aspects, and is not able to enjoy the legacies of all these innovations. Pediatric cataract is morphologically and anatomically different from adult cataracts, and ophthalmologists should have precise knowledge of basics of pediatric ocular biometry and IOL power calculations. Implantation of IOL in growing eye needs undercorrection, and titration of IOL power. What and how much to implant. So major concepts are measurement regarding keratometry and axial length, choices of IOL, IOL power calculation formulae, and what target refraction to be set, and long-term issues one has to consider about visual axis opacification and obscuration, and myopic shift. Problems can occur because of miscalculation of IOL power, and problems can occur because of increase in axial length, resulting in myopic shift. Various researchers have found that at birth, mean axial length is 16.6 to 17 millimeters, and mean keratometry is 51.2 diopters. This keratometry, from 51.2 diopters, decreases to 43.5 diopters within six months of age, and this is the famous graph given by Gordon and Donzis, showing that in the first two years of age there is rapid eye growth, and later on there is a slower phase of growth, up to the age of 10 years, and after 10 years, the axial length stabilizes. Do pediatric eyes with cataract behave in a similar manner? Trivedi et al. did a study on 299 eyes, and they found that average keratometry reading of 54.39 with a standard deviation of 3.08. Age and axial length had a significant linear relationship, and steeper K values were found from birth to 6 months of age, and they found that girls had steeper corneas when compared with boys, monocular cases were steeper than bilateral cases, and for unilateral cataract, the eye with the cataract had a significantly steeper cornea compared to the other eye. Others have reported that unilateral cataract were steeper than those of bilateral cataract. While Asbell et al. reported that corneas from eyes with persistent fetal vasculature were steeper than the average for normal eyes at that age. What about biometry? Trivedi, in a survey of 310 eyes, reported that girls had shorter axial lengths, and that the African-American subjects had longer axial length than the Caucasians. They found that eyes with unilateral cataract had shorter axial length than those with bilateral before 60 months of age, but after 60 months of age, they had longer axial length compared to eyes with bilateral cataract. Axial lengths of unilateral cataractous eyes were shorter than non-cataractous eyes. And in this series they found that axial length to be 20.5 with a standard deviation of 2.9 millimeters, which is quite different from the series from Gordon and Donzis. And they reported axial length to be 21.9 with a standard deviation of 1.6 millimeters. And if you see this difference of standard deviation, this data itself suggests that these pediatric cataractous eyes are abnormal to begin with, and therefore they can behave differently. Therefore it is very difficult to predict at what amount these eyes will grow later. And with this study, they suggested that there are three phases of eye growth in children with pediatric cataract. A rapid postnatal phase from birth to six months of age, and during this age, the axial length increases from 0.6 millimeters per month. A slower infantile phase from 6 to 18 months of age, in which there is growth of 0.19 millimeters per month, and later there is a slower juvenile phase from 18 months forward, and axial length increases at a very slow pace of 0.01 millimeters per month. Others also reported similar and different axial length findings in these cataractous eyes, but all of them reported these axial lengths in a limited number of eyes, so no conclusion can be drawn from their studies. Three major components of IOL power calculations are biometry, formulas, and clinical variables. Biometry include calculation of axial length, corneal power, and hence IOL power calculation. And in formulas, one has to see which generation to use. First generation, second, third, or fourth generation, or to use a theoretical or regression formula, or combination of theoretical and regression formulae. And one has to see whether one needs to do personalization of A constants. Clinical variables include patient needs and special circumstances, and even if you have calculated correct IOL power, you need to titrate and customize your IOL power according to patient needs. So here comes poll question two: Do you perform biometry yourself in all pediatric cataracts? First, yes, most of the time, second option is not at all, and third is mostly rely on biometrist or your technician. Still waiting for the response. Yeah, great to see that most of you perform biometry yourself in your cases, and 26% of you say that they rely on technician or biometrist. So biometry can be done by conventional ultrasound biometry or by optical biometry. Conventional ultrasound biometry can be done by applanation or contact method, and immersion A scan method. Optical biometry can be done by time domain-based partial coherence interferometry, by LENSTAR by Haag-Streit, by the Swept source from Carl Zeiss Meditec, or the ALADDIN. The accuracy of this optical biometry has proven to be very good in adult cataractous eye, but in pediatric eye, we do not have a lot of good information about these optical biometers. Measurement of axial length can be done by handheld or manual refractometer. Error in measurement can arise because there is lack of fixation under anesthesia. And like keratometry, A scan biometry should be performed for both eyes. And both this keratometry and A scan should be done before the insertion of speculum, and saline should be put regularly, to prevent any erroneous K reading because of dry cornea. Once you are done with keratometry, A scan measurement, and biometry, one can switch to pachymetry, retinal examination, and refraction. Ultrasound biometry uses 10 megahertz ultrasonic waves to obtain parameters like axial length, anterior chamber depth, and lens thickness. And axial length is inversely proportional to this ultrasound velocity. And there are different A scan machines available worldwide, and therefore the surgeon has to choose technical specification provided by their A scan manufacturers. If you compare contact versus immersion method, contact ultrasound method has certain advantages. It’s very convenient. It is accurate with trained biometrists, but it causes corneal compression, and in adults, it has shown that contact methods can give rise to 0.24 to 0.32 millimeter error. This corneal compression is more likely in pediatric eyes because of low corneal and scleral rigidity. Immersion method uses a scleral cup, and it can be filled with a coupling fluid. With this, the readings are more accurate and there is no risk of any errors from excess pressure applied. The only disadvantage is that it is a very cumbersome procedure, and one needs to take extra time in the operation theater to do this procedure, and you need a very trained biometrist and ultrasonographer. You should always make sure you are getting the correct reading. And if you are using a machine which is having both contact and immersion method, never forget to change your settings from contact to immersion mode. What are the characteristics of a good quality A scan? A good quality A scan should have anterior lens echo which is 90% or more of maximum height. A posterior lens echo which is between 50% to 75% of maximum. A retinal echo which is 75% or more of maximum. And scleral echo should be well defined. Orbital fat should descend quick. The echo rise must be clear, and takeoff angle must be 90 degrees. If the beam is aligned to optic nerves rather than macula, you can have erroneous readings, and in that case, there will be no scleral and no orbital fat echoes. So the ultrasonographer, biometrist, or surgeon should constantly look on the oscilloscope screen to rule out erroneous readings, and once you are sure that your A scan is of good quality then only can consider it to be a valid measurement. Here comes the poll question 3. What is your preferred choice of ultrasound sonography? First is applanation and second is immersion method. We are waiting for response from panelists. Yeah, it sounds good. That most of you prefer applanation method of ultrasound sonography. Some of you prefer the immersion or contact method. In a 2009 email survey, which is unpublished data — it was this email survey, AAPOS members, it stated that 82.4% of surgeons reported contact A scan compared to 17.6% who reported using the immersion technique, but this data is very old. It is of 2009. And the recent publication, about Delphi process in pediatric cataract management, pediatric experts have a common consensus that A scan immersion — they prefer A scan immersion for examination under anesthesia, and for cooperative child in clinic, they prefer IOLMaster in comparison to A scan. Trivedi et al. compared axial length measurements by contact and immersion techniques in pediatric cataractous eye, and they found that axial length given by contact technique was on average 0.27 millimeters shorter than immersion technique, and this difference was because of the result of anterior chamber depth, rather than lens thickness value. And if axial length by contact technique is used for IOL power calculation, you will end up with 1 diopter stronger IOL power. So they suggest that if you are using applanation biometry, rely on measurements with the greatest anterior chamber depth. And to minimize postoperative myopic errors in refraction by using immersion A scan, you should use routinely immersion A scan for children having cataract surgery. Now, what about prediction error and absolute prediction error? Prediction error is predicted refraction minus actual refraction. And here the sign of the error is taken into account. Why? In absolute prediction error, it’s predicted refraction minus actual postoperative refraction, and here sign of error is not taken into account. Trivedi et al. found that absolute prediction error by contact and immersion method was not significantly different, but prediction error was significantly different between contact and immersion method. Ben-Zion and Daniel et al. found that absolute prediction error between contact and immersion method was not statistically significant. And Ben-Zion in their study found that axial length given by immersion scan were 1 millimeter larger than contact methods. But the study done by them was done in two different groups of immersion. One group by immersion, and one group by contact method. What is the importance of accuracy? Why we are so behind the calculation of axial length? 0.1 millimeter error in axial length can give rise to 0.25 to 0.3 diopter postop surprise, and therefore 1 millimeter error can give rise to 2.5 to 3 diopter postop surprise. And in longer eyes, this 1 millimeter error drops to 1.75 diopters of surprise, and in short eyes, this 1 millimeter error jumps to 3.75 diopters postop surprise. So one has to be very careful in calculating axial length in very short eyes. So for any IOL power calculation and biometry methods, employ a well trained technician and biometrist, regularly calibrate your manual keratometers and IOLMasters. Carefully evaluate IOLMasters for reliability. In the case of IOLMaster 500, look for SNR ratio. Keep contact lenses out for 2 to 3 weeks before keratometry. And whenever you are planning any IOL undercorrection, always check twice before implanting IOL into pediatric eye. So here comes the poll question 4. What biometry method are you using for pediatric cataract? Applanation in examination under anesthesia and optical biometry for cooperative child? Immersion in examination under anesthesia and optical biometry for cooperative child? Do you prefer to do applanation in all cases, or immersion in all cases? So let’s see for the quick poll results. Yeah. Great. Most of you, 50% of you, prefer to do applanation in examination under anesthesia and optical biometry for cooperative child. And 23% of you are using applanation in all cases. So there are different types of optical biometers available and provided by different manufacturers across — worldwide. And IOLMaster 500 is a time domain based partial coherence interferometer, it is non-contact optical biometer, easy to use, accurate, and highly reproducible. Studies have shown the reliability and validity of partial coherence interferometry for measurement of ocular axial length in children by IOLMaster 500. Quinn et al. did a study and found highly precise eye length measurements in children age 3 to 12 years. They found that 20% of children were cooperative on IOLMaster 500 and they were able to get readings in all cases. The cases in which they were not able to get readings was not because the child was uncooperative. Rather, it was the cataract density which doesn’t allow IOLMaster to take measurements. So if you see in the left hand side… This is the display of IOLMaster 500. And it gives you axial length in millimeters. Corneal keratometry reading. Optical anterior chamber depth. And it gives you various formulas for IOL power calculation, like Haigis, SRKII, Haigis-L, and prior refractive surgery. You can get whatever target refraction you want to set, and you can have different IOL powers on this screen. And here in my right hand side, this display shows the axial length for IOLMaster. And here if you see in the center, there is a narrow primary maxima peak. And this peak in center should be tall and thin, and it should have a thin terminal peak. And it should be followed by lesser, secondary, tertiary, and quaternary maxima. The axial length is calculated from corneal vertex to retinal pigment epithelium. Our ultrasound machine gives the measurement from corneal vertex to anterior limiting membrane only. You should have an SNR value of 1.6 in case of IOLMaster 500. Ultrasound aims at optical axis of eye to get measurement. By partial coherence interferometry, in very high myopic eyes, you can have different readings if you are using ultrasound, and you can have a higher reading when you are using a PCI-based IOLMaster. And therefore postoperatively, you can get a surprise of 4 to 5 diopters, if there is a difference of 2 to 3 millimeters in axial length. So to avoid any staphyloma surprises and surprises in high myopic patients, if the cataract is less dense and the child is cooperative, better to go with a PCI-based optical biometer. So this is a printout from IOLMaster 500. And here you can see the right eye and left eye measurements are given. There is the axial length, K1 and K2, sphere, and cylinder. The scan was taken in 2015. And for this particular formula, because in the right eye it was 17.17 and in the left it was 17 millimeters, this is for secondary IOL implantation — here you can see the machine gives you different IOL powers depending on various lenses and their lens constant. The IOLMaster 700 is a newer technology. It is a Swept Source-based OCT biometry. And in addition to optical biometry, it also offers imaging across the entire length of the eye. And it gives faster A scan compared to existing optical biometers and applies B scan technology to show images across the length of the eye. It shows lens thickness and axial length and gives you a keratometric leading, gives you a point of fixation, gives value of pupillometry, and eye to eye diameter. And all of these are displayed in this screen, along with their standard deviation of variability. And here in my right hand, if you see, is the printout from IOLMaster 900. And it depicts axial length, anterior chamber depth, keratometric reading, and lens thickness. And if you see this line, it gives you a correct estimation that the patient is using his point of fixation, and hence a reliable reading. So I would like to share a few examples, where we couldn’t do IOLMaster 500 or where IOLMaster 500 was not possible because of a dense cataract, and we were able to obtain all measurements with the IOLMaster 700. This was a boy, ten years old. And here you can see that this boy had a dense posterior polar cataract. And in this image, you can clearly see the dense posterior polar cataract. Line of fixation is going along where the patient is fixing. And it is quite accurate. And in this case, we were able to obtain all readings of excellent keratometry and anterior chamber depth. And all these readings had the correct specified standard deviation of variability. This is the second example of posterior polar cataract. The posterior capsular dehiscence. This 12-year-old girl presented to us, and she had dense posterior cataract, and here you can see in this image that along with this posterior cataract, you can see a less intense image, which suggests that there could be a possibility of posterior capsular dehiscence. And intraoperatively, we found that there was one, and on removing the cataract, you could appreciate a posterior defect in the capsule. This figure displays the IOL calculation given by IOLMaster 700, and in the top screen, you can see the machine provides you various formulas and in this particular case, because the axial length was normal, SRK/T formula was used for IOL power calculation. And below you can see the machine displays the various IOL power, depending upon the lens constant and depending upon the material of lens. This is, again, an example where you can see how IOLMaster beautifully gives you lens thickness and lamellar cataract. But role of lens thickness in IOL power calculation in pediatric cataract is still debatable. We are not having any data to support that lens thickness in pediatric cataract can play a major role in accuracy — in postop accuracies. Another example is of intumescent cataract. Here you can see the lens thickness is very bulgy. And the lens thickness is around 4.4 millimeters. You can easily appreciate the anterior chamber depth is very less, and for this particular case, the IOLMaster gives axial length of 19.9 millimeters, and for this case, we use the Barrett Suite formula. The advantage of that is that it takes the posterior corneal measurement, and in adults it has been shown to give a very precise posterior refraction in short eyes. In this particular case, you can see the IOL power calculation for accurate lens was 34.5 diopters. This is another interesting case of anterior pyramidal cataract. And most of the authors described anterior pyramidal cataract as Hershey’s Kisses because of their similarity to Hershey’s Kisses chocolate. This case presented to us with defective vision in right eye. It was a three and a half-year-old boy. And we were not able to get any measurement with IOLMaster 500. But with IOLMaster 700, we were able to get the axial length measurement. And IOL power calculations were possible. And here in this image you can see beautifully how the anterior pyramidal cataract looks and simulates these Hershey’s Kisses. So after calculation by IOLMaster 700, IOL power came to be 28 diopters. And considering the age of the child, the IOL power implanted was 26 diopters. So 2 diopters undercorrection was done to have a hypermetropia of 2 diopters postoperatively, and postoperatively, the child had 20/40 vision, with +2 diopter sphere. And the child is in follow-up with us and doing occlusion in left eye. So I shared these examples, where IOLMaster 500 was not possible. And IOLMaster 700 gave us appropriate results. But limitation of IOLMaster 700 is that in the presence of very dense intumescent cataract and total cataract, it is not able to give you reliable measurement. And therefore for uncooperative children, and for children with dense cataracts, the immersion method remains still gold standard. We presented a poster about lens thickness in different morphological pediatric cataracts using IOLMaster 700 at World Congress of Pediatric Ophthalmology and Strabismus. And we found the average lens thickness, axial length, and anterior chamber depth and spherical equivalent were quite close to the other reported findings by immersion methods. And we found an interesting finding, that lamellar cataract had less lens thickness, compared to posterior subcapsular cataract and total cataract. And there was no correlation between axial length and lens thickness in most of these patients. But the limitation of this study was that we have included only 35 eyes of 19 patients. So most studies are required with IOLMaster 700 to know the reliability of this machine in pediatric cataracts. If we compare IOLMaster 500, LENSTAR LS900, and IOLMaster 700, we can see the IOLMaster uses partial coherence interferometry, and a semi-conductor diode laser of 780 nanometer wavelength. It doesn’t give us any information about lens thickness or corneal thickness. And gives us only anterior chamber measurement. LENSTAR is based on optical low coherence reflectometry, uses a superluminescent diode laser, and gives us additional information about corneal thickness, lens thickness, anterior chamber depth, axial length, white to white distance, eccentricity from visual axis, and the point of fixation. While IOLMaster 700 from Carl Zeiss uses a tunable laser with a wavelength of 1055 nanometers, and it is quite faster, compared to other existing optical biometers. It gives us corneal thickness, lens thickness, anterior chamber depth, axial length, white to white measurement, and pupil diameter. There are a few studies comparing the axial length in optical biometry versus ultrasound in the pediatric eye. One study by Lenhart et al. reported that axial length measurement obtained by PCI obtained 22.41 with a standard deviation of 1.37, while with immersion method, they noted 22.27 with a standard deviation of 1.26. And they reported that in all eyes with axial length of 23 or less, the PCI values were less than or equal to immersion ultrasonography. Gursoy et al. reported Lenstar values to be higher compared to ultrasound method. Carkeet reported that IOLMaster measurements were larger than contact ultrasound, 0.14 millimeters larger when it was done by IOLMaster, but this was in pediatric non-cataractous eye. It is important to determine the target under postoperative correction. So when an IOL is implanted in a child, a myopic shift must be expected, and therefore one has to plan undercorrection ahead. The various normograms proposed by different pediatric experts — Enyedi et al. suggested +6 if age at surgery is 1. If age at surgery is 2 years, you can plan +5, and at age of 7, you can plan for emmetropia. Plager et al. suggested that for a child age 3, you can plan +5 diopters of hypermetropia, and after 10 years of age, you should plan for emmetropia. While Trivedi and Wilson suggested similar normograms to Plager et al. They suggested at age of 1 and 2 year, one should aim at +6 and +5 of hypermetropia. Guidelines for undercorrection of intraocular lens power in children suggested that guidelines by Enyedi et al. give you absolute good refractive outcomes at the age of 7 years, and under age of 2 years, you should do minimal undercorrection, and you should do less undercorrection as proposed by Enyedi et al. They found that 80% of children had appropriate refractive error. Dahan et al. proposed that if axial length is 17 millimeters, IOL power should be 28 diopters, at 21 millimeters, you can implant 22 diopters of IOL power. And for children less than 2 years, better to do 20% undercorrection, and for children between 2 to 8 years, do 10% of undercorrection. And for children more than 8 years, plan for emmetropia. Now, here comes the poll question 5. What IOL power calculation formula do you prefer for your patients? SRK2, SRK/T and Holladay 2, Hoffer Q for short eyes and SRK/T for long eyes, or some other formula? Still waiting for panelists’ opinion. Yeah. Most of you are preferring SRK 2 formula. And 20% of you preferred Hoffer Q for short eyes and SRK/T for long eyes, and 30% of you prefer SRK/T and Holladay 2. It’s good to see this. So no single formula is accepted as gold standard. Theoretical formulas, combined with regression formulae, like SRK-T, Holladay 1 and 2, Hoffer Q and Haigis are preferred over older regression formulas like SRK and SRK2. Vasavada et al. studied this and found that Holladay 2 and SRK/T had the least predictive error. Personalizing the lens formula constant did reduce the personalization error significantly for all formulae except Hoffer Q. In our previous slides, we have seen that certain normograms suggested by various experts — but then also what power to implant and how much to undercorrect is a multifactorial decision, and you have to customize for each and every child, based on variable factors like age at the time of cataract surgery, status of the fellow eye, visual acuity, compliance of the child’s family to glass/occlusion, implantation in bag or sulcus, secondary IOL implantation, and parents’ refractive error. If surgery is done bilaterally, leave more hypermetropia. In poor complaints or uniocular cataract, better to leave less hypermetropia, and in dense amblyopia, better to have lesser hypermetropia. Children with cataract and myopia can be left more hypermetropic. Infant aphakia treatment study was a randomized multicenter trial comparing the treatment of unilateral aphakia in patients under 7 with primary IOL implant contact lens, and they found no difference between the two and found more complications, adverse events, and surgeries in the IOL group than the contact lens group. Most common adverse event was visual axis opacification, and most common additional intraoperative surgery was clearing of visual axis opacification. So one should be very cautious when implanting IOL in a child less than 7 months of age. Another important question is: What IOL to implant? AcrySof hydrophobic acrylic lenses are most preferred, while three piece acrylic lenses are preferred for sulcus fixation. You should avoid silicone and hydrophilic acrylic lenses, and incidence of posterior capsular opacification and postoperative inflammation has been reported to be significantly less with acrylic lenses. PMMA is another good option. It has a good memory, and it is a good option for developing countries where there are financial concerns and AcrySof cannot be implanted in every case. Secondary IOL implantation can be done in-bag when you are able to break the adhesions between posterior and anterior capsule. And if is not possible and your primary posterior capsulorrhexis is too large, better plan for sulcus fixation. There are various studies on sutured and sutureless scleral fixated IOLs in pediatric cases. But in long-term results for scleral fixation, retinal detachment, dislocation of lenses, breakage of suture, and glaucoma has been reported. So one has to think what IOL you have to implant for secondary IOL. Iris fixated lens seems to be very good option for correcting aphakia in children. But again, the question is long-term follow-up, in terms of how much endothelial cell count these lenses will cause, and to what amount of glaucoma you can get later on. Pediatric toric IOL is again a debatable question. One needs to do a very precise toric IOL power calculation. And IOL rotation can be postoperatively — can be a major issue. In this particular case, with a postop… Preoperative astigmatism of 2.5 diopters, with a with-the-rule astigmatism, a toric IOL was implanted. It was a 15-year-old child. And postoperatively they found vision of 20/20 with residual astigmatism of 0.5 diopters astigmatism, and with eye trace aberrometry, it was evident that it was decrease in not only aberration, but point spread function was also improved. But again, one has to be very cautious implanting pediatric toric IOL in children less than 10 years, and a recent study has given good visual outcomes of toric intraocular lenses in children with developmental cataract and preexisting corneal astigmatism. But again, it is a debatable issue. Multifocal IOL in pediatric cases, again, is a controversial issue. And multiple images — and there’s no evidence-based data that multifocal lenses are superior to monofocal ones. Multiple images by these multifocal lenses can cause amblyopia, and children can complain of glare and have decreased contrast sensitivity with these lenses. PCO, tilt, and decentration can deteriorate optical performance of these lenses. So we have discussed pretty good evidence-based data so far. And a recent publication for the use of the DELPHI process in pediatric cataract helps to identify areas of consensus and disagreement among pediatric experts in pediatric cataract management. And this paper elaborates what international pediatric cataract experts opine on intraoperative, preoperative, and postoperative issues on pediatric cataract management. Capsulotomy by femtosecond lasers and Zepto have leapt into the field of pediatric cataract. Laser may be able to perform both anterior and posterior capsulotomy, but safety and outcomes of femtosecond laser assisted cataract surgery remains to be determined. And precise IOL power calculation still remains the main challenge in pediatric cataract. So I would like to conclude with these points. Technology and innovations may come. Choose best for your pediatric patient. And always, before operating a child, have this question in your mind: If this were your child. The future lies in your hand and the future of your country. Thank you very much for attending this Cybersight live webinar at the end of this year. And welcome to questions. If there are any questions and queries, we can have discussion on this. Yeah. Waiting for questions from participants. Yeah. So one of the participants had asked: What age do you prefer toric IOL? Personally, I would not prefer toric IOL in cases less than 10 years of age. Because in these pediatric cases, you have to do measurement before induction of anesthesia. And there is high chance that these cases with with-the-rule astigmatism can later behave differently, so personally I won’t advocate to do toric IOL in cases below less than 10 years. But in some reports, people have claimed that they have got good results in children less than… In children more than age of 4 years. But I don’t have personally experience on very young children. Yeah, there’s another question. Whether you would prefer IOL in children less than a year. It depends. If it is unilateral cataract, we would prefer to place IOL. But again, it should be more than 6 to 7 months of age. And if it is a bilateral cataract, you can wait up to age of 1 year. Even after 1 year of age, you can implant IOL. This one. Another question. Apart from heredity, what are the factors in induced congenital cataract in this modern era? Cataract is multifactorial. There are various — not only these cardiacs are hereditary in nature, but in developing countries, you can see congenital rubella to be more responsible for causing these cataracts. While in developed countries, we will see more metabolic syndromes. And more syndromic association with cataract. And besides these cataracts, you can have cataract induced because of trauma. There’s one more question. In myopic eyes, should we undercorrect more? Yeah. It is better to do more undercorrection in these myopic eyes, because more myopia is expected with increasing age. So better to leave more hypermetropia in myopic eyes, and this you can again titrate, if parents are — there is history of myopic parents. In rubella cataract, what is your choice of IOL? Yeah, this is a very good question. Most of the rubella cataracts are having very small cornea, very less pupillary size. Very small. Their iris is quite different from normal eyes. Therefore, if corneal diameter is more than 10.5 millimeters, it is better to place IOL. And it is better to place IOL in bag, and acrylic lenses are preferred. Because it is seen that if pupil doesn’t dilate, preoperatively, it can suggest that later these eyes are having high risk of glaucoma. Another question is: In a center where there is no biometry accessibility, what do you do with IOL power determination? Good question. It is very difficult to do this. But I think that if you are having a keratometer and any axial length… If you’re able to measure it, then it is better to implant IOL power. Because these growing eyes can behave differently, so it is very difficult to answer this question. But I have seen people preferring lenses of higher power. 23 and 22 diopter, when they are not having any access to any of these biometers. Yeah. One more question we got. What you give as a treatment preoperatively and postoperatively? So preoperative, it is better to start antibiotic drops 6 times a day. And in cases where there is some watering or if there is history of any probing done for congenital nasolacrimal duct, better to have a cultural sensitivity test, and postoperatively, you can have a combination of a steroid and antibiotic, or you can use the antibiotic and steroid as a separate treatment. And better to give a cycloplegic drop like cyclopentolate for one or two weeks. And in very small children, you can use even atropine. But you have to use it very cautiously, because if patients are putting these atropine drops or ointment more, there is risk of fever and flushing. And all atropine-induced side effects. So another question is: What formula is preferred in children? Personally, I prefer if axial length is more than 21 millimeter diameter, SRK/T formula gives a good result. And for axial length less than 21 millimeter, it is better to use Hoffer Q formula. And even for eyes with axial length more than 21 millimeters, Holladay 2 formula is also a good option. Do you do posterior capsulorrhexis in every case? No, the decision of posterior capsulorrhexis is again debatable. Some prefer to do up to age of only 6 years. But some prefer to do it up to age of 8 to 9 years. It depends upon the availability of YAG capsulotomy machine. And also if you are sure that you are able to follow the patient for a long time, you can leave PC intact up to age of 8 years. But if you are not sure that patient will come for a proper follow-up, it is better to do posterior capsulorrhexis even in children greater than age of 8 years. And in cases of mentally challenged children and children with nystagmus, you can do posterior capsulorrhexis up to any age. I think we are done. And rest of the questions we can… If you want, we can send you answers through email. And again, I thank Cybersight for giving me this opportunity, and I also appreciate to all of you that before new year and Christmas all of you joined us for this live webinar.

Thank you again and wish all of you a merry Christmas and happy new year ahead. Thanks a lot.

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December 22, 2017

Last Updated: October 31, 2022

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