Implantation of an intraocular lens (IOL) in the eyes of select. Biometry Data from Caucasian and African-American Cataractous Pediatric Eyes

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1 Biometry Data from Caucasian and African-American Cataractous Pediatric Eyes Rupal H. Trivedi and M. Edward Wilson PURPOSE. To report the biometry data of pediatric cataractous eyes (randomly selected single eye in bilateral cases; cataractous eye in unilateral cases) and to compare the biometry data of the unilateral cataractous eye with the data of the corresponding noncataractous fellow eye. METHODS. The study was a chart review/analysis of immersion A-scan biometry measurements, excluding traumatic cataract or lens subluxation. RESULTS. Three hundred ten eyes were examined at surgery. The mean age was months; globe axial length (AL), mm; anterior chamber depth (ACD), mm; and lens thickness (LT), mm. During the first 6 months of life, AL increased 0.62 mm/mo, 0.19 mm/mo from 6 to 18 months, and 0.01 mm/mo during 18 months to 18 years of age. The girls had shorter ALs than did the boys (P 0.090), and the African-American subjects had longer ALs than did the Caucasians (P 0.001). Eyes with unilateral cataract had shorter ALs than those with bilateral cataracts before 60 months of age, but had longer ALs than the eyes with bilateral cataracts after 60 months of age. Eyes of the female subjects had shallower ACDs than those of male subjects (P 0.026). Eyes with unilateral cataract had shallower ACDs than those of eyes with bilateral cataracts (P 0.001). In the children 5 years of age, LT was significantly greater in eyes with unilateral cataract than in those with bilateral cataract. AL of the unilateral cataractous eye was significantly shorter than that of the fellow noncataractous eye before 6 months of age (P 0.001). CONCLUSIONS. This study begins to lay the groundwork for calculating pediatric IOL power in cataractous eyes by using pediatric ocular measurements. (Invest Ophthalmol Vis Sci. 2007;48: ) DOI: /iovs Implantation of an intraocular lens (IOL) in the eyes of select children undergoing cataract surgery has become the standard of care for pediatric aphakia. 1 Although surgical techniques have improved over the past several years, IOL power calculation issues have not necessarily kept up. Biometry of the eye is an important step when deciding IOL power. Currently, pediatric IOL power is calculated with formulas designed for adult eyes and based on adult biometry data. To design IOL power calculation formulas specifically for pediatric eyes, it is From the Miles Center for Pediatric Ophthalmology, Storm Eye Institute, Department of Ophthalmology, Medical University of South Carolina (MUSC), Charleston, South Carolina. Supported in part by National Eye Institute Grant EY14793 (vision core); the Grady Lyman Fund of the MUSC Health Sciences Foundation; and an unrestricted grant to MUSC-SEI from Research to Prevent Blindness, Inc. Submitted for publication March 4, 2007; revised May 6, 2007; accepted August 21, Disclosure: R.H. Trivedi, None; M.E. Wilson, None The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked advertisement in accordance with 18 U.S.C solely to indicate this fact. Corresponding author: Rupal H. Trivedi, MUSC, Storm Eye Institute, Room 519, 167 Ashley Avenue, Charleston, SC ; trivedi@musc.edu. important to explore similar data from pediatric eyes. Various publications have reported globe axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) in children with clear lenses 2 5 and in adults with cataractous lenses. 6,7 Our objective was twofold: to report the AL, ACD, and LT in pediatric cataractous eyes measured with the immersion A- scan ultrasound technique and to compare the data of the unilateral cataractous eye with those of the corresponding noncataractous fellow eye. METHODS The research adhered to the tenets of the declaration of Helsinki. The project received an exempt status from the Human Investigation Review Board of the Medical University of South Carolina. It entailed a chart review of all patients who had undergone cataract surgery at or before 18 years of age at the pediatric ophthalmology clinic of the Storm Eye Institute between November 1991 and November We excluded eyes with traumatic cataract or lens subluxation. We also excluded eyes in which the AL was not available at the time of cataract surgery. As race is known to influence biometry results in children and most of our patients are either Caucasian or African-American (a few are Hispanic or Asian), we have included only data of Caucasian and African-American patients, to avoid the possibility of confounding effects. In bilateral cases we randomly selected one eye for analysis, whereas for unilateral cases, data from the cataractous eye were analyzed. Data collected include age at surgery, gender, race, and laterality of cataract. We also collected biometry data for AL, ACD, and LT. AL, ACD, and LT measurements typically were obtained by immersion techniques, with the child under general anesthesia and through a dilated pupil. Regression analysis and analysis of variance (ANOVA) were used for statistical analyses. For gender, race, and laterality analysis, a t-test for independence was used based on the results of the F-test for equality of variance. For unilateral cataracts, we used a paired t-test to compare AL, LT, and ACD of eyes with cataract with those measurements in the fellow eye with a clear lens. RESULTS Biometry Data of Pediatric Cataractous Eyes Three hundred ten eyes were analyzed, with a mean age at cataract surgery of months (median, 27.50; range, ); mean AL of mm (range, ); ACD of mm (range, ); and LT of mm (range, ). Table 1 shows the mean AL per age group. In Table 2, the first 2 years of life are divided into age groups, showing the mean AL per each age group (Table 2A) and the post hoc analysis (Table 2B). Table 3 shows descriptive statistics of mean AL as they relate to gender, race, and laterality of cataract per the indicated age groups. Twelve of the 13 eyes with an AL 25 mm were African-American. In a scatterplot of age versus AL, Figure 1 shows a logarithmic linear trend that supports that Investigative Ophthalmology & Visual Science, October 2007, Vol. 48, No. 10 Copyright Association for Research in Vision and Ophthalmology 4671

2 4672 Trivedi and Wilson IOVS, October 2007, Vol. 48, No. 10 TABLE 1. AL Measurements in Unilateral and Randomly Selected Single Eyes of Pediatric Patients with Bilateral Cataracts, Categorized by Age Age* (y) n Length (Mean SD) 95% CI Range Total Data are expressed in millimeters. * Post hoc analysis (Tukey test) revealed that AL at 1 year was significantly different from that in all other age groups (P 0.001). AL of 1- to 2-year-old children was significantly different from that in children older than 10 years (P 0.02). No other pair reached significance. the greatest change occurs early in life, especially during the first 6 months. The results of regression analyses using AL as an independent variable are shown below. Age demonstrated a significant linear relationship with AL. 1. AL (3.09 log of age in months)(r ; P 0.001). 2. AL (3.03 log of age in months) (0.85 race) (R ; age: P 0.001, race: P 0.001). Race is a dummy variable, where African-American 1, Caucasian AL (0.04 age in months) (R ; P 0.001). Although age showed a significant linear relationship with AL, transformation of age to log of age better fit the normality assumption for linear regression. Logarithmic transformation of age explains more variation in AL than does age (70% when log of age is used and 41% with age). Although the addition of race added significantly to the model already containing age (P 0.001), the addition of gender and cataract laterality in a regression model that already contains log of age did not significantly explain the linear relationship (P 0.27 and 0.18, respectively). Linear regression analysis revealed that during the first 6 months of life, AL increased by 0.62 mm per month. From 6 to 18 months of age, it increased by 0.19 mm per month and after 18 months, by 0.01 mm per month or 0.12 mm per year. Tables 4 and 5 show descriptive statistics of mean ACD and LT, respectively, as they relate to gender, race, and cataract laterality, per the indicated age groups. Figure 2 is a scatterplot of age versus ACD, showing a logarithmic linear trend that supports that the greatest change occurs early in life, especially during the first 6 months, similar to that seen with AL (Fig. 1). Figure 3 illustrates the linear positive relationship of AL to ACD. The scatterplot of Figure 4 (age versus LT) shows little linear relationship. Figure 5 presents AL versus LT in a scatterplot and shows a positive linear relationship. Figure 6 presents ACD versus LT in a scatterplot and shows a negative relationship. Biometry Data of Pediatric Unilateral Cataractous Eyes Compared with Their Corresponding Fellow Eyes Tables 6, 7, and 8 show mean AL, ACD, and LT, respectively, in unilateral cataractous eyes when compared with measurements of their fellow eyes with clear lenses. DISCUSSION Biometry Data of Pediatric Cataractous Eyes Investigators have reported AL, ACD, and LT in noncataractous pediatric eyes 3,4 or cataractous adult eyes. 6,7 In this study, we used immersion A-scan measurements to determine the values for these categories in pediatric cataractous eyes. Various publications in the literature have reported that growth of the eye is influenced by visual experience Visual deprivation leads to excessive eye elongation. 8,9,11 13 Growth of cataractous eyes may have been influenced by two mechanisms: Amblyopia may lead to a longer AL, and associated ocular anomalies may be associated with a shorter AL. Thus, we were interested in determining the effect of cataract on AL. It is well documented in the literature that the human eye undergoes extensive growth in the postnatal period. 2,3 The increase of approximately 7 mm in AL from birth to adulthood requires a reduction of approximately 30 D of total refractive power to maintain an emmetropic state. In our series, the mean AL during the first month of age was mm, which increased to mm in children 10 to 18 years of age, showing 7.19 mm in axial growth. Larsen 2 reported a rapid, post-natal phase with an increase in AL of 3.7 to 3.8 mm in the first year and a half of life; followed by a slower, infantile phase from years 2 to 5, with an increase in AL of 1.1 to 1.2 mm; and finally a slow, juvenile phase lasting until the age of 13 years, with an increase of 1.3 to 1.4 mm. Subsequently, Gordon and Donzis 3 noted that the greatest increase in AL TABLE 2. AL Measurements during First 2 Years of Life A. AL Measurements in Unilateral and Randomly Selected Single Eyes of Pediatric Patients with Bilateral Cataracts Age (mo) n Length (Mean SD) 95% CI Range Total Data are expressed in millimeters. B. Post Hoc Analysis of Data in A < <001 <001 <001 < <001 <001 <001 < <001 <001 < <001 < <001 < <001 <001 < <001 <001 <001 < <001 <001 <001 < Age ranges are expressed in months. Significant differences are in bold (P 0.05; Tukey test).

3 IOVS, October 2007, Vol. 48, No. 10 Biometry of Cataractous Pediatric Eyes 4673 TABLE 3. AL Measurements in Unilateral and Randomly Selected Single Eyes of Pediatric Patients with Bilateral Cataracts, in Reference to Gender, Race, and Laterality of Cataract Birth All Ages Gender F (n 49) (n 20) (n 32) (n 45) (n 146) M (n 45) (n 20) (n 44) (n 55) (n 164) P Race Caucasian (n 75) (n 34) (n 53) (n 70) (n 232) African-American (n 19) (n 6) (n 23) (n 30) (n 78) P <0.001 <0.001 Laterality Unilateral (n 73) (n 23) (n 41) (n 53) (n 190) Bilateral (n 21) (n 17) (n 47) (n 120) P Total (n 94) (n 40) (n 76) (n 100) Data are the mean number of subjects SD. Age ranges are in months. Bold data are significant at P (n 310) occurred in the youngest age groups. By the age of 2 to 3 years, the rate of growth slowed to approximately 0.4 mm per year over the next 3 to 4 years. After the age of 5 or 6 years, the AL increased approximately 1 mm for the next 5 years. No significant increase in AL was reported after 10 or 15 years of age. Cook et al. 14 noted 0.64 mm per month growth in AL in premature infants, which is similar to our results of 0.62 mm. In our series, from 6 to 18 months of age, AL at surgery was greater by 0.19 mm per month of age. After 18 months, AL at surgery was greater by 0.01 mm per month of age, or 0.12 mm per year. This finding suggests a rapid, postnatal phase from birth to 6 months of age (earlier than the birth to 18 months reported by Larsen 2 ), followed by a slower, infantile phase from 6 to 18 months of age, and finally a slow, juvenile phase from 18 months forward. Larsen reported that the longitudinal growth terminates at the age of 13 years or is minimal after this age. Our study is not a longitudinal study and cannot adequately determine the age at which axial growth stabilizes. However, as seen in Table 1, the mean AL of the 9- to 10-yearold children was mm, whereas the mean AL of the children 10 to 18 years of age was mm, suggesting an average 0.95 mm more mean AL in 10- to 18-year-old children compared with 9- to 10-year-old children. Further studies looking at longitudinal axial growth in the second decade are planned. The AL at 1 year-of-age was significantly different from all other age categories (Table 1). Isenberg et al. 15 noted that at term, the mean AL was 16.2 mm, which correlates with our mean AL of mm in infants 1 month of age. In a longitudinal study, Pennie et al. 16 noted the mean AL at 1 month of age to be mm 0.41, increasing to mm at 1 year. Although our study is not longitudinal, our data of cataractous eyes showed a mean AL of mm at 0 to 1 month of age and mm at 6 to 12 months of age. AL at 12 to 18 months was not significantly different from that of 18 to 24 months (Table 2B). Fan et al. 17 noted a mean AL mm in children undergoing IOL implantation at 6 months of age (n 22) and mm in children 7 to 12 months of age (n 12). These values seem higher than our results; however, we have analyzed all FIGURE 1. Scatterplot of A-scan measurements of AL at surgery in relation to age. Axial Length (mm) Age (months)

4 4674 Trivedi and Wilson IOVS, October 2007, Vol. 48, No. 10 TABLE 4. ACD Measurements in Unilateral and Randomly Selected Single Eyes of Pediatric Patients with Bilateral Cataracts, in Reference to Gender, Race, and Laterality of Cataract Birth All Ages Gender F (n 33) (n 21) (n 30) (n 102) M (n 23) (n 15) (n 30) (n 40) (n 108) P Race Caucasian (n 43) (n 27) (n 38) (n 52) (n 160) African-American (n 13) (n 6) (n 13) (n 50) P Laterality Unilateral (n 42) (n 28) (n 123) Bilateral (n 14) (n 15) (n 23) (n 87) P Total (n 56) (n 33) (n 51) (n 70) (n 210*) Data are the mean number of subjects SD. Age ranges are expressed in months. Bold data are significant at P * ACD data were not available for 100/310 (32.3%) eyes. consecutive eyes with cataract, whereas Fan et al. have analyzed only eyes that received an IOL implantation. Selection bias (not implanting IOL in eyes with microphthalmos) may explain the discrepancy in AL. For noncataractous pediatric eyes, Mutti et al. 18 noted a mean AL of mm in 3-month-old infants, as opposed to our results in cataractous eyes of mm at the same age. At 9 months of age, these mean values were and mm (Mutti et al. and our study, respectively). Although the measurement techniques are different, it is clear that variation in AL was high in our cataractous eyes when compared with noncataractous pediatric eyes in the literature. Mayer et al. 19 noted that the variability in spherical equivalent refraction decreases significantly with age. Hoffer 7 reported 7500 adult cataractous eyes (mean age, years) as having a mean AL of mm. Our results in patients aged 10 to 18 years show a mean AL of 23.2 mm. This suggests that AL may continue to grow at a slow rate up to or even after 18 years of age. However, additional studies of a longitudinal nature are necessary to answer this question. Data comparison of noncataractous eyes in the literature and our cataractous eyes will help us better understand the effect of cataract on AL in children. We have shown that the overall mean AL of pediatric cataractous eyes ( mm) 20 is significantly different (P 0.001) than the overall mean AL of pediatric noncataractous eyes ( mm) as described by Gordon and Donzis. 3 More important, the standard deviation was nearly two times more in eyes with cataract TABLE 5. LT Measurements in Unilateral and Randomly Selected Single Eyes of Pediatric Patients with Bilateral Cataracts, in Reference to Gender, Race, and Laterality of Cataract. Birth All Ages Gender F (n 32) (n 17) (n 20) (n 30) (n 99) M (n 22) (n 15) (n 29) (n 40) (n 106) P Race Caucasian (n 41) (n 26) (n 37) (n 52) (n 156) African-American (n 13) (n 6) (n 12) (n 49) P Laterality Unilateral (n 40) (n 28) (n 121) Bilateral (n 14) (n 14) (n 21) (n 84) P Total (n 54) (n 32) (n 49) (n 70) Data are the mean number of subjects SD. Age ranges are expressed in months. Bold data are significant at P * LT data were not available for 105/310 (33.9%) eyes (n 205*)

5 IOVS, October 2007, Vol. 48, No. 10 Biometry of Cataractous Pediatric Eyes Anterior Chamber Depth (mm) 5.5 FIGURE 2. Scatterplot of A-scan measurements of ACT at surgery in relation to age Age (months) 6.5 Anterior Chamber Depth (mm) 5.5 FIGURE 3. Scatterplot of A-scan measurements of ACD at surgery in relation to AL Axial Length (mm) 6.5 Lens Thickness (mm) 5.5 FIGURE 4. Scatterplot of A-scan measurements of LT at surgery in relation to age Age (months)

6 4676 Trivedi and Wilson IOVS, October 2007, Vol. 48, No Lens Thickness (mm) Axial Length (mm) FIGURE 5. Scatterplot of A-scan measurements of LT at surgery in relation to AL. than in those without ( 2.9 mm vs. 1.6 mm). This difference is a very important factor to keep in mind; that is, these cataractous eyes are abnormal to begin with, which may also lead to variations in postoperative growth. Eyes with cataract showed a shorter AL in the first 12 months of life (cataractous, mm; noncataractous, mm). In the first 12 months of life, the standard deviation was almost three-times that of in eyes without cataract ( 2.0 mm vs. 0.7 mm). Sex-linked differences in the AL have been reported in the literature. 2,15,21 In cataractous eyes, the girls had a shorter AL than did the boys (Table 3, mm vs mm, P 0.09). Larsen 2 reports shorter mean AL in noncataractous eyes of girls than the mean AL in noncataractous eyes of boys (23.92 mm vs , P 0.001). Isenberg et al. 15 noted that the eyes of male infants grow faster than those of female infants (P 0.001). Significantly longer eyes were found in African-American patients than in Caucasian patients (Table 3, mm vs mm, P 0.001). AL differences between the two races became more visible as age advanced. Pursuing the involvement of amblyopia or familial refractive error was beyond the scope of this study, however. Gwiazda et al. 21 note that they did not find a difference in axial dimensions in different ethnic groups. Kleinstein et al. 22 note significant differences in the prevalence of refractive error among ethnic groups (African- American, Asian, Hispanic, and Caucasian), even after controlling for age and sex. However, they did not find a significant difference in the prevalence of myopia in Caucasians (4.4%) when compared with African-Americans (6.6%). We found that eyes with unilateral cataracts overall had a shorter mean AL than those with bilateral cataracts (Table 3, mm vs mm, P 0.003). This effect was seen until 60 months of age (P 0.05). Eyes with cataract may also be associated with ocular anomalies (e.g., microphthalmos) leading to shorter AL. However, in children beyond 60 months of age, unilateral cataractous eyes were longer than bilateral cataractous eyes (Table 3, mm vs mm, P 0.02). Form-deprivation and/or deprivational amblyopia are likely to lead to a longer AL. However, the effect of amblyopia on AL may not be very apparent during the first few months of life. In addition to genetic factors, it is the balance between associated ocular anomalies and amblyopia that affect the AL in pediatric cataractous eyes. We have not looked at genetic factors. Lorenz et al. 23 have reported that in unilateral cataract, there is a trend toward an increased AL. In bilateral cataract, the eyes were shorter than normal, especially when surgery was performed during the first 6 months of life. Eyes between 6 and 12 months of age tended to have normal to increased AL at the time of surgery. Lorenz et al. 23 further reported that in unilateral cat- Anterior Chamber Depth (mm) Lens Thickness (mm) FIGURE 6. Scatterplot of A-scan measurements of ACD at surgery in relation to LT.

7 IOVS, October 2007, Vol. 48, No. 10 Biometry of Cataractous Pediatric Eyes 4677 TABLE 6. ALs in Unilateral Cataractous Pediatric Eyes Compared with Those in Fellow Eyes with Clear Lenses Age (mo) n Cataract Eye Fellow Eye P Total 184* Data are expressed as mean millimeters SD. Bold data are significant at P * Fellow eye AL data were not available for six eyes. aract, 5 of 12 eyes examined at the time of surgery were 7% to 16% longer than their age-matched control eyes. Griener et al. 24 reported that in unilateral cases, between 2 and 6 months of life the mean AL was 18.7 mm. Moore 25 reported that in eyes at a mean age of 3.7 months (range, 1.3 6) the mean AL was mm (range, ). They reported that the AL in all but one patient was greater than the average AL of normal neonates in their practice. Rasooly et al. 12 reported that patients with bilateral congenital cataract had significantly shorter eyes than those with unilateral disease. Rasooly et al. 12 have excluded eyes with evident microphthalmos. Like AL, ACD showed a linear association with the log of age. With increasing age, ACD also increased. This increase in ACD may be a result of an increase in AL rather than decreasing LT. Larsen 5 reported a similar ACD increase in a pediatric population with noncataractous eyes. In a longitudinal study from birth to the first year-of-life, Pennie et al. 16 noted an increase in ACD during the first year-of-life, which correlates with our results. Female subjects have a shallower anterior chamber than do male subjects. Foster et al. 26 noted shallower ACs in women than in men. Variation in ethnicity is observed only from 6 to 18 months of age. Eyes of patients with unilateral cataract had significantly shallower ACDs than did those with bilateral cataract. During the overall growth period, there appears to be a real sex-determined difference in ACD of approximately 0.1 mm, with the deeper ACD found in boys. Our results also show that ACDs have a rapid growth during the first few months of life. Garner et al. 27 reported a significant difference in the rate of increase in ACD between nonmyopic and myopic groups (P 0.015). Garner et al. 27 noted thinning of the crystalline lens in their pediatric population without cataract, noting that lens thinning continues to age 18 years, although the rate decreases with increasing age. Our data from cataractous eyes do not support these findings in noncataractous eyes. With increasing AL in our series, LT increased. Hydration of the cataractous lens may have masked this thinning in our pediatric population. Although our study was not longitudinal, the older children in our series had thicker lenses. In a longitudinal study from birth to the first year of life, Pennie et al. 16 noted no change in LT. TABLE 7. ACDs in Unilateral Cataractous Pediatric Eyes Compared with Those in Fellow Eyes with Clear Lenses Age (mo) n Cataract Eye Fellow Eye P Total 118* Data are expressed as mean millimeters SD. Bold data are significant at P * Fellow eye ACD data were not available for 65 eyes. TABLE 8. LTs in Unilateral Cataractous Pediatric Eyes Compared with Those in Fellow Eyes with Clear Lenses Age (mo) n Cataract Eye Fellow Eye P Total 116* Data are expressed as mean millimeters SD. Bold data are significant at P * Fellow eye lens thickness data were not available for five eyes. Biometry Data of Pediatric Eyes with Unilateral Cataract Compared with Their Corresponding Fellow Eyes In young eyes with unilateral cataract, the cataractous eyes had a shorter mean AL than did their fellow eyes (Table 6, mm vs , P 0.095), although the difference was not significant. Here again, as age advances, eyes with unilateral cataract have a mean AL longer than their fellow eyes with clear lenses. Kugelberg et al. 28 reported their results in 12 children with unilateral congenital cataract (age range, days). All these eyes had a shorter AL (median, mm) than did their fellow eye (median, mm) and a median age of 103 days (range, 4 418). In cases of unilateral cataract, eyes with cataract have a significantly shallower anterior chamber (P 0.001) than do fellow normal eyes. The changes in ACD in relation to age are more marked during 0 to 6 months of age and in children greater than 5 years of age. Larsen 5 noted that from birth to the age of 13 years, the mean ACD increased from 2.37 to 3.70 mm in boys and from 2.39 to 3.62 mm in girls. The increase in ACD took place in three growth phases: a rapid postnatal phase from birth to the age of years with an increase of approximately 0.9 to 1.0 mm, a slower infantile phase from 1 to 7 years with an increase of 0.3 to 0.4 mm, and a slow juvenile phase from 8 to 13 years of age with an increase of barely 0.1 mm. To the best of our knowledge, our study is the first of its kind to report biometry data of pediatric cataractous eyes. The sample size of 310 eyes of 310 patients is acceptable considering the rarity of the disease. The use of immersion A-scan measurements for biometry is a strength of the study. However various literature sources have used different techniques of measurement (applanation, immersion, optical biometry) to perform the A-scan; therefore, these variations must be kept in mind when comparing our data with those in the previous literature. Our study was not a longitudinal study, because obvious limitations make it impossible to design such a study, to gather preoperative biometry data. The results of our study should be interpreted cautiously. We have reviewed our data in relation to age at surgery instead of age at cataract diagnosis, as it is not always possible to be certain about the age at onset of cataract. We did not look at type of cataract or at any influence cataract type might have had on various ocular parameters. Pupil dilatation may have affected ACDs. However, because we performed these measurements in patients under anesthesia, we had to hasten the procedure and therefore to dilate these eyes for detailed evaluation of the cataract. Lack of fixation while measuring AL under general anesthesia adds a further limitation to obtaining reliable biometry readings. However, unless the child is able to cooperate for reliable awake measurements, no better option exists. Looking at the quality of the A-scan image (e.g., vertical retinal spikes and double rising corneal echo) helped to obtain

8 4678 Trivedi and Wilson IOVS, October 2007, Vol. 48, No. 10 the correct measurements in the absence of fixation. We used the services of an experienced ultrasonographer for our measurements, to reduce the likelihood of error. The following results were drawn from our study: (1) Eyes with cataract followed a logarithmic trend in changing AL as age advanced. At the younger ages, eyes with cataract had a shorter AL compared with their normal fellow eyes or data of the pediatric population without cataract. With advancing age, eyes with cataract had a longer AL than did their normal fellow eyes. (2) During the first 6 months of life, AL at surgery increased by 0.62 mm with each month of age. From 6 to 18 months of age, it increased by 0.19 mm per month of age and after 18 months, by 0.12 mm for each year of age. (3) The measurements of cataractous eyes tended to be different from those of the noncataractous eyes. Not only did the mean results differ but, more important, the SD was nearly twice that of the normal population. (4) Cataractous eyes in the girls had shorter ALs compared with those of the boys. (5) Eyes of the African- American subjects had longer ALs compared with those of Caucasian subjects. (6) Eyes with unilateral cataract had shorter ALs than eyes with bilateral cataract during the earlier years, but had longer ALs during later childhood. (7) Eyes of the girls had shorter ACDs than those in the boys. (8) Eyes with unilateral cataract had shallower ACDs than those with bilateral cataract and shallower ACDs when compared with their fellow eyes with a normal lens. Data from these series provide an overview of the limits of normal biometry data in African-American and Caucasian pediatric cataractous eyes. The results of the AL measurements from these children can be specified as within or outside the 95% CIs in Tables 1 and 2A. For eyes that yield values outside the 95% CIs we recommend repeating the biometric examination. The results of this study have begun to lay the groundwork for formulas that can be used calculate pediatric IOL power based on measurements obtained from pediatric cataractous eyes. References 1. Wilson ME Jr, Bartholomew LR, Trivedi RH. Pediatric cataract surgery and intraocular lens implantation: practice styles and preferences of the 2001 ASCRS and AAPOS memberships. J Cataract Refract Surg. 2003;29(9): Larsen JS. The sagittal growth of the eye. IV. Ultrasonic measurement of the axial length of the eye from birth to puberty. Acta Ophthalmol. 1971;49(6): Gordon RA, Donzis PB. Refractive development of the human eye. Arch Ophthalmol. 1985;103(6): Zadnik K, Manny RE, Yu JA, et al. Ocular component data in schoolchildren as a function of age and gender. Optom Vis Sci. 2003;80(3): Larsen JS. The sagittal growth of the eye. 1. 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