Mean Corneal Diameter Research Articles

Early surgery of bilateral congenital cataracts in eyes with microcornea

Purpose: To report the results of early surgery of congenital cataracts in eyes with microcornea. Methods: We retrospectively reviewed the charts of 22 eyes of 11 patients. All patients underwent limbal approach lensectomy and anterior vitrectomy within 12 weeks. The mean corneal diameter at surgery ranged from 7.0 to 9.0 mm. The mean age at surgery was 7.7 ± 3.3 weeks (range, 2-12 weeks); the follow-up period was 111 ± 59 months (range, 36-196 months). Results: Other preoperative ocular abnormalities included iris hypoplasia in 10 eyes and persistent fetal vasculature in 3 eyes.

Central Corneal Thickness and Corneal Diameter in Patients With Childhood Glaucoma

To determine and compare the central corneal thickness (CCT) and corneal diameter among groups of patients with childhood glaucomas and assess the relationship between CCT and corneal diameter in these patients. A multicenter observational case series using prospective and retrospective data. Patients from the Scheie Eye Institute, Children's Hospital of Philadelphia, and Emory and Vanderbilt Medical Centers with childhood glaucomas were eligible to participate. Retrospective data on CCT and corneal diameter of these patients were collected when available; otherwise, patients were asked to return to the ophthalmology clinics for measurements. Patients with corneal edema or central corneal scarring were excluded. One hundred eighty four glaucomatous eyes from 109 patients (median age = 9.0 y; age range = 0 to 60 y) were included. The mean CCT (+/-SE) was 651.1+/-63.5 microm for aphakic, 528.7+/-38.5 microm for Axenfeld-Rieger, and 563.4+/-67.9 microm for 1 degrees infantile eyes. The mean corneal diameter in aphakic, Axenfeld-Rieger, and 1 degrees infantile glaucoma eyes were 11.2+/-1.0, 12.5+/-0.9, and 13.2+/-1.2 mm, respectively. There was a significant difference in CCT and in corneal diameter between aphakic and 1 degrees infantile glaucoma eyes, and between aphakic and Axenfeld-Rieger eyes (P < 0.0001). There was a negative correlation between CCT and corneal diameter in all eyes (r = -0.41, P < 0.0001). Patients with aphakic glaucoma are different from those with congenital glaucoma or Axenfeld-Rieger in CCT and corneal diameter. A patient with pediatric glaucoma and a larger corneal diameter was more likely to have a thinner CCT. Attention should be paid to the CCT of patients with childhood glaucomas for interpretation of intraocular pressure.

Normal Periocular Anthropometric Measurements in the Turkish Population

Purpose: To evaluate the ocular and periocular anthropometric measurements of Turkish subjects. Methods: Corneal diameter, horizontal and vertical palpebral fissure, vertical brow-nasal distance, inter-outer canthal distance, inter-inner canthal distance, interpupillary distance, bridge height, lid crease, brow height, levator function, head circumference and interorbital distance were measured in 706 eyes of 353 subjects. Results: In men, the mean corneal diameter was 10.5 mm, horizontal palpepral fissure was 30.0 mm, vertical palpepral fissure was 9.7 mm, vertical brow-nasal distance was 36.9 mm, inter-outer canthal distance was 91.3 mm, inter-inner canthal distance was 30.7 mm, interpupillary distance was 60.6 mm, nasal bridge height was 4.7 mm, lid crease was 6.0 mm, pretarsal skin height was 2.3 mm, brow height was 9.7 mm, levator function was 14.4 mm, interorbital distance was 99.1 mm and head circumference was 58.0 cm. In female subjects these measurements were 10.3 mm, 30.0 mm, 9.9 mm, 35.1 mm, 90.1 mm, 30.2 mm, 60.1 mm, 4.3 mm, 5.9 mm, 2.1 mm, 9.9 mm, 14.6 mm, 95.8 mm and 55.9 cm, respectively. Conclusion: In this study we obtained the anthropometric measurements of ocular and periocular structures in Turkish subjects. Knowledge of normal values in a population can be important in the manufacture of spectacles and in clinical and surgical practice.

Case series of angle-closure glaucoma after laser treatment for retinopathy of prematurity

Laser photocoagulation is the current treatment standard for severe retinopathy of prematurity (ROP). Uncommon, but well recognized complications include cataract, and vitreous and retinal hemorrhage. Angle-closure glaucoma after laser photocoagulation for ROP is rare. The purpose of this study was to identify additional cases of angle-closure glaucoma following laser treatment for ROP. Five eyes of four patients with angle-closure glaucoma following laser treatment for ROP were identified by three ophthalmologists at separate institutions between 1997 and 2001. Demographic and clinical data were obtained from medical records. Clinical and surgical findings associated with the diagnosis and management of angle-closure glaucoma following ROP laser were evaluated. The following data were collected (mean (range)): gestational age, 26.8 (24 to 29) weeks; birth weight, 833 (570 to 1062) g; age at laser treatment for ROP, 35 (33 to 37) weeks; number of laser burns, 1598 (930 to 2400); and time to diagnosis of angle-closure glaucoma, 3.6 (2 to 5) weeks. Three of five eyes had objective data for intraocular pressure (IOP) and corneal diameter with mean IOP 41 mm Hg (35 to 44) and mean corneal diameter 11.1 mm (10.25 to 11.5). Initial treatment included topical and systemic medications. Three eyes required surgical intervention. Angle-closure resolved in all cases with normalization of IOP. Follow-up (5 months to 3.6 years) showed that affected eyes tended to be more myopic than unaffected fellow eyes (mean spherical equivalent -6.5 vs -4.7 diopters). Angle-closure glaucoma can develop following laser treatment for severe ROP. Medical, and frequently surgical, intervention provides effective management.

Anterior chamber width measurement by high-speed optical coherence tomography

To measure anterior chamber (AC) width and other dimensions relevant to the sizing of phakic intraocular lenses (IOLs) with a high-speed optical coherence tomography (OCT) system. Cross-sectional observational study. Both eyes of 20 normal volunteers. A novel high-speed (4000 axial scans/second) OCT prototype was developed for anterior segment scanning. The system uses long wavelength (1310 nm) for deeper angle penetration, rectangular scanning for undistorted imaging, and short image acquisition time (0.125 seconds) to reduce motion error. Three horizontal cross-sectional OCT images (15.5 mm wide and 6 mm deep) of the anterior segment were obtained from each eye with real-time image display to guide centration on the corneal apex. Image processing software was developed to correct for image warping resulting from index transitions. Anterior chamber dimensions were measured using computer calipers by 3 expert raters (ophthalmologists). Analysis of variance was used to determine interrater, interimage, right versus left eye, and intersubject standard deviation (SD) of OCT measurements. Anterior chamber width (recess to recess), AC depth, and crystalline lens vault as measured by OCT; external white-to-white (WTW) corneal diameter (CD) as measured by Holladay-Godwin gauge. The mean AC width was 12.53+/-0.47 mm (intereye SD), and the mean corneal diameter was 11.78+/-0.57 mm. Optical coherence tomography measurement of AC width has good repeatability from image to image (SD, 0.134 mm), but there was significant difference between raters (SD, 0.215 mm). Estimation of AC width from WTW CD by linear regression was relatively inaccurate (residual SD, 0.41 mm). The mean AC depth was 2.99+/-0.323 mm (intereye SD), with repeatability of less than 0.001 mm (interimage SD), and the mean crystalline lens vault was 0.39+/-0.27 mm with 0.023 mm repeatability. Reproducible OCT AC biometry was demonstrated using a high-speed OCT prototype. Further improvement in reproducibility may be achieved by automating the measurements with a computer. Direct OCT AC width measurement may improve sizing of angle-supported AC IOLs over conventional estimation by WTW CD. The measurement of AC depth and lens vault also may be useful for other types of phakic AC IOLs.

Myopia predicts better outcome in persistent hyperplastic primary vitreous.

Persistent hyperplastic primary vitreous (PHPV) is a congenital disorder that presents with a spectrum of ocular anomalies, including cataracts, microphthalmia, and hyaloid vessel remnants. Severe visual loss due to secondary glaucoma and retinal detachment is common. This report evaluates the visual outcome of a variant of PHPV with myopia not associated with glaucoma. The records of 23 consecutive patients with the diagnosis of PHPV (all unilateral) from October 1992 to August 1995 were reviewed. All but three patients had a cataract extraction procedure and all underwent amblyopia therapy. Eyes with a phakic myopic refractive error (Rx) or aphakic refractive correction < or = 8.5 diopters (D) in the immediate postoperative period were designated as myopic. Six patients were in the myopic group (Group 1) and 17 in were the nonmyopic group (Group 2). The mean age of diagnosis was 21.1 months in Group 1 versus 2.0 months in Group 2, with a comparable follow-up period of 36 months. The mean preoperative Rx of Group 1 was -7.78 D. The mean aphakic Rx of Group 2 was +18.29 D. Average axial length measurement determined by echography was 22.46 mm in Group 1 and 14.03 mm in Group 2. The mean corneal diameter was 11.3 mm in Group 1 vs 8.9 mm in Group 2. In Group 2, seven eyes developed retinal detachment and four developed glaucoma. These complications did not develop in Group 1 during the follow-up period. Overall functional visual acuity was better in Group 1, with a median visual acuity at final follow up of 20/160, as compared with light perception for Group 2. PHPV eyes with myopia were not detected as early as the typical PHPV eyes, primarily because of less media opacification and near-normal corneal diameters. These eyes showed a more favorable visual outcome as they were less likely to develop typical PHPV-related postoperative complications. Myopic PHPV eyes may require a different management approach.