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. Pourcelot's 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.

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.

Can non-ophthalmologists screen for retinopathy of prematurity?

BACKGROUND: Dilation and tortuosity of the posterior pole vessels ("plus disease") is a poor prognostic sign and may indicate the presence of threshold or pre-threshold retinopathy of prematurity (ROP). Because stage 3 ROP appears rarely in the absence of posterior pole vascular abnormalities, we prospectively evaluated the ability of non-ophthalmologists (4th-year medical students, pediatric residents, and nurse practitioners) to identify abnormalities in the retinal blood vessels of infants undergoing examinations for ROP. METHODS: Fifty infants weighting less than 1600 g at birth were examined between 32 and 40 weeks after conception. Prior to ophthalmological examination, non-ophthalmologist examiners graded posterior pole vessels as normal or abnormal based on ophthalmoscopic appearance. One hundred twenty-one ocular examinations were performed using the teaching mirror of the indirect ophthalmoscope, 179 using the direct ophthalmoscope. The indirect ophthalmoscopy was performed simultaneously by an ophthalmologist who evaluated the posterior pole vessels for abnormalities prior to conducting a peripheral fundus examination on either eye. RESULTS: Testing sensitivity for the non-ophthalmologist examiners using direct and indirect ophthalmoscopy was 96% and 92%, respectively. Combining the results from direct and indirect ophthalmoscopy, the Clopper-Pearson 95% sensitivity confidence interval for identifying abnormal arterioles and venules was 82% to 99%, with a point estimate of 95%. CONCLUSION: These data suggest that non-ophthalmologist examiners can detect posterior pole vascular abnormalities in premature infants. If properly trained, they could possibly play a role in screening or follow-up examinations for ROP.

The predictive value of posterior pole vessels in retinopathy of prematurity.

Dilation and tortuosity of the posterior pole vessels "(plus disease)" is a sign of poor prognosis and may be associated with threshold or prethreshold retinopathy of prematurity (ROP). We have found that normal posterior pole vessels are a reliable marker for the absence of stage 3 ROP. One hundred thirty-two consecutive premature infants weighing less than 1600 g at birth underwent ROP examinations between 32 and 40 weeks' postconceptional age. The status of the posterior pole vessels was compared to peripheral retinal pathology. Vascular findings in the posterior pole were graded 0, 1, 2, or 3, with 0 representing normal arterioles and venules and 3 representing plus disease. The remainder of the fundus examination was recorded using the international Classification of ROP, then converted to a severity scale based on zone and stage of ROP. For each infant, only one examination representing the most severe stage of ROP reached prior to treatment or spontaneous regression was used for data analysis. There was a highly significant Spearman's rank correlation (rs = 0.65) between the posterior pole vascular abnormalities and the severity of ROP in the retinal periphery. Clinically important ROP was not found in any patient with normal posterior pole vessels (grade 0) and stage 3 disease was usually associated with both venous and arterial vascular abnormalities (grades 2 or 3). When ocular examination of premature infants is difficult because of poor dilation of the pupil, hazy media, or medical instability, normal appearance of the posterior pole vessels can be a reassuring finding if it is necessary to postpone complete fundus examination in infants at risk for ROP.

Current trends in the use of intraocular lenses in children.

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.

Intraocular lenses for pediatric implantation: biomaterials, designs, and sizing.

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.

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

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.

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

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.

Surgery on the normal eye in Duane retraction syndrome.

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.

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.

Trabeculectomy with 5-fluorouracil vs single-plate Molteno implantation.

We compared the results achieved in 22 consecutive patients who underwent single-plate Molteno implantation, with those achieved in a matched group who had trabeculectomy with postoperative 5-fluorouracil. Six months following surgery, the average intraocular pressure (IOP) in the Molteno group was 15.4 +/- 8.0 mm Hg, and in the trabeculectomy group, 16.1 +/- 5.6 mm Hg (P = .920). A mean of 1.4 antiglaucoma medications were being used in each group (P = .776). Complications following Molteno implantation included six tube revisions and three flat anterior chambers; following trabeculectomy, eight serous choroidal detachments and nine positive Seidel tests. This study suggests that Molteno implantation and trabeculectomy with adjunctive 5-fluorouracil provide similar IOP control, but that the two procedures are associated with different types of complications.

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

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.

Binocularity in accommodative esotropia.

One hundred twenty-seven medical records of patients with accommodative esotropia met our inclusion criteria and were analyzed. All included patients were within 10 prism diopters of orthophoria and had stereopsis and other binocular sensory test results recorded at their latest visit. Bifixation, defined as stereopsis of 50 arc seconds or better, was present in 31 patients (24%) with an average follow up of 89 months. Monofixation (peripheral fusion) was present in the remaining 96 patients (76%) with an average follow up of 84 months. Patients with bifixation were less likely to have presented with constant esotropia (19% vs 39% [P = .04]) and were more likely to be aligned within 8 delta of orthophoria in their first glasses (84% vs 21% [P < .0001]). No patient with bifixation had constant esotropia longer than 4 months. In addition, patients with bifixation were less likely to have worn bifocals (39% vs 59% [P = .09]), or undergone esotropia surgery (23% vs 62% [P < .0001]). These data suggest that maintenance of bifixation is possible in accommodative esotropia if the eyes are straightened before or shortly after the esodeviation becomes constant. With this early therapy, amblyopia and deterioration of ocular alignment are also less likely.

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.