EttaLeah C. Bluestein

Current trends in the use of intraocular lenses in children

Abstract We present an overview of current practice patterns as they apply to intraocular lens (IOL) implantation in children. Two hundred and thirty‐four members of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) and 1,039 members of the American Society of Cataract and Refractive Surgery (ASCRS) responded to a questionnaire. Forty‐six percent of AAPOS respondents and 27% of ASCRS respondents reported that they are currently implanting IOLs in children. Although the majority have implanted lenses in children older than six years, 16 AAPOS members and 41 ASCRS members reported implanting IOLs in patients in their first two years of life. Eighty‐four percent of the respondents use the continuous curvilinear capsulorhexis technique of anterior capsulotomy in children. When a primary posterior capsulotomy is performed, 63 ASCRS surgeons (38%) reported using posterior continuous curvilinear capsulorhexis. Fixation of an IOL in the ciliary sulcus in a child was acceptable to 67% of the surgeons; however, 86% would not consider implanting an anterior chamber IOL in a child. Implications of the survey data are discussed.

Inhibition of posterior capsule opacification: The effect of colchicine in a sustained drug delivery system

ABSTRACT We investigated the effect of colchicine in a sustained drug delivery system on posterior capsule opacification (PCO) in rabbit eyes. A polymer matrix wafer, which diffused colchicine at a steady rate, was implanted in the capsular bag of 34 eyes after the lens material was removed by endocapsular phacoemulsification. Three different drug concentrations were used in the rabbit eyes, which were compared with control eyes containing the polymer matrix wafer without colchicine. The mean PCO score was highest in the control group without colchicine and increased steadily over 12 weeks. The rate of PCO formation in all eyes treated with colchicine was significantly lower than in the control group. There was no statistically significant improvement in PCO inhibition with the higher colchicine dosages. Side effects included inflammatory anterior chamber reaction and corneal and retinal complications and were most notable with the highest drug concentration. Slow release of colchicine reduces PCO formation in the rabbit. The optimal biocompatible dosage must be carefully determined and warrants further investigation.

Comparison of mechanized anterior capsulectomy and manual continuous capsulorhexis in pediatric eyes

Abstract Performing a continuous curvilinear capsulorhexis (CCC) can be more difficult in children than in adults because the capsular bag is more elastic. In this study we compared two capsulectomy techniques in pediatric eyes: creating a mechanized circular anterior capsulectomy using a vitrector and creating a conventional smooth‐edged curvilinear tear or CCC using a forceps or needle. We used 18 pairs of eyes (36 eyes) obtained postmortem from children ranging in age from four days to 16 years. The mechanized vitrector‐cut capsulectomy was unsuccessful in only one eye (from a 16‐year‐old child) in which a radial tear developed. Manual CCC was unsuccessful in six eyes, all from children less than five years of age. We conclude that mechanized circular capsulectomy is not only easier to perform in very young eyes than manual CCC, but it is also safe and creates a capsular opening that resists radial tearing. This mechanized technique gives the surgeon an alternative to use in pediatric eyes in which standard manual CCC may be difficult to perform and control.

Intraocular lenses for pediatric implantation: Biomaterials, designs, and sizing

Abstract Posterior chamber intraocular lenses (IOLs) are being implanted in children with increasing frequency. However, with rare exceptions, only IOLs designed for adults are currently available. These lenses may be difficult to insert into small eyes. Since the pediatric crystalline lens is smaller than that of adults and because the capsular bag does not continue to grow after lensectomy, it is worthwhile to determine the biomaterials, designs, and sizes that may be appropriate for pediatric implantation. In a study of 50 pediatric eyes obtained postmortem, we have documented an estimated growth curve for the developing crystalline lens between birth and 16 years of age. Ninety percent of crystalline lens growth occurs during the first two years of life. Based on these data and this study using the Miyake posterior view analysis of implanted standard and prototype IOLs, we recommend the following: Clinical trials of capsular IOLs, downsized to approximately 10.0 mm diameter, are appropriate for children under two years of age. Capsular IOLs are defined as flexible open‐loop, one‐piece, all poly(methyl methacrylate), modified C‐loop designs made specifically for in‐the‐bag placement. Because the rapid growth phase of the lens is complete by the age of two, we believe that downsizing the IOL is not necessary after this age unless axial length measurements indicate an unusually small eye. Standard flexible 12.0 mm to 12.5 mm diameter capsular IOLs can be safely implanted. Such lenses could be tolerated throughout life, obviating the need for later IOL exchange.

Anterior segment ischemia after strabismus surgery

Surgery on the extraocular muscles of the eye is generally consisted a safe procedure which is associated with low morbidity and mortality. While infrequent, intra-operative complications occasionally occur. Tenotomy of multiple rectus muscles can result in interruption of the vascular supply to the anterior segment of the eye. Anterior segment ischemia (ASI) may result. This article reviews the complication of anterior segment ischemia as a result of strabismus surgery and its potential for producing permanent visual loss.

Dimensions of the pediatric crystalline lens: Implications for intraocular lenses in children

As surgeons gain more experience with the implantation of posterior chamber intraocular lenses (IOLs) into the capsular bag in children, the minimum age for which implantation is advised may continue to be lowered. Accurate sizing of an IOL intended for in-the-bag fixation may depend on knowledge of the size of the capsular bag. In order to develop a growth curve for the normal crystalline lens and hence the capsular bag, 50 pediatric autopsy eyes ranging in age from 1 day to 16 years were obtained postmortem and measured within 24 hours after enucleation. Mean crystalline lens diameter was 6.00 mm at birth, 6.80 mm at 2 months, 7.1 mm at 3 months, 7.66 mm at 6 to 9 months, 8.4 mm at 21 months, 8.5 mm at 2 to 5 years, and 9.3 mm at 16 years. The post-lensectomy capsular bag size at each respective age is 1 mm larger. While age was a predictor of crystalline lens size, corneal diameter and globe axial length were better predictors of crystalline lens size. These data and accompanying linear regressions may be helpful in designing appropriate IOLs for pediatric patients.

Color doppler imaging of the central retinal artery in premature infants undergoing examination for retinopathy of prematurity.

PURPOSE Recent attempts have been made to quantify blood flow velocity in the central retinal artery (CRA) of adults using color Doppler imaging (CDI). Although retinal vascular abnormalities are the hallmark of severe retinopathy of prematurity (ROP), normal values have not been established for CRA blood flow velocity in premature infants. METHODS CDI of the CRA was successfully performed on 43 eyes in 22 infants (postconceptional ages 32 to 39 weeks) before the infants underwent examination for ROP. Peak systolic velocity (PSV) and end diastolic velocity were recorded from at least 1 eye of each patient. Pourcelots resistive index was then calculated for each eye studied. RESULTS Mean PSV for patients with no ROP (n = 6) was 7.2 +/- 1.5 cm/s, whereas those with any degree of ROP excluding plus disease (n = 9) had a mean PSV of 8.9 +/- 1.8 cm/s. Of the patients with ROP and plus disease (n = 7), the mean PSV was 7.0 +/- 1.6 cm/s. There were no statistically significant differences among these 3 groups (P= .08). CONCLUSIONS CDI can be successfully performed on preterm infants and yields values lower than those previously reported in healthy adult subjects. PSV in the CRA may be higher in subjects with ROP in the absence of plus disease; however, further study is needed to determine whether these differences are significant.

Pediatric cataract surgery and intraocular lens implantation techniques: a laboratory study

Abstract The use of primary posterior capsulectomy and anterior vitrectomy during pediatric intraocular lens (IOL) implantation has been advocated as a means of preventing the development of posterior capsule opacification. In this study, we used pediatric eyes obtained postmortem to compare two different sequences in the surgical procedure: (1) anterior capsulectomy, lens substance removal, primary posterior capsulectomy with anterior vitrectomy, and IOL implantation in the capsular bag; (2) anterior capsulectomy, lens removal, IOL implantation in the capsular bag, and primary posterior capsulectomy with anterior vitrectomy. Both sequences could be safely performed in the laboratory setting while maintaining stable capsular fixation of the IOL. Placing the IOL in the capsular bag was easier when the posterior capsule was intact (sequence 2). However, both techniques appear feasible for clinical use. Surgeons not familiar with mechanized primary posterior capsulectomy can gain clinically relevant experience by operating on pediatric autopsy eyes in a laboratory setting.

Tight versus loose scleral flap closure in trabeculectomy surgery

Thirty-two consecutive trabeculectomy patients were randomized to receive a tight scleral flap closure (15 eyes) with postoperative laser suture lysis, or a loose scleral flap closure (18 eyes) to determine differences in the surgical results. Three months postoperatively no statistical difference in intraocular pressure (loose closure 15.1 ± 3.3 mm Hg, tight closure 15.0 ± 3.6 mm Hg,p > 0.05) or number of glaucoma medicines (loose closure 1.6, tight closure 1.3,p > 0.05) existed between treatment groups. In the early postoperative period, no statistical difference between groups was observed in the anterior chamber depth, visual acuity or intraocular pressure (p > 0.05). Laser suture lysis was performed without complication in nine patients with a statistically significant reduction in intraocular pressure (p < 0.01). This study suggests, by the technique used, that no obvious benefit exists in using a tight versus a loose scleral flap closure when performing a trabeculectomy.

Surgery on the Normal Eye in Duane Retraction Syndrome/Surgery on the Normal Eye in Duane Retraction Syndrome: Discussion

Duane retraction syndrome is a well-described congenital eye movement disorder whose management is still controversial. Various surgical strategies have been advocated, usually limited to the involved (restricted) eye to eliminate a face turn or a manifest deviation in the primary position. However, surgery on the normal eye has the potential to expand the field of single binocular vision as well as restore primary position alignment. In patients with mild-to-moderate duction deficiencies in the restricted eye, we have used very large recessions or posterior fixation sutures on the normal eye to create matching duction limitations, which in some cases produce a wider range of fusion postoperatively.