Faculty Bibliography

PURPOSE: To evaluate the changes and trends in the number and characteristics of contact lens-related ulcers (CLRUs) and to compare the results with those of previously published series at our institution. METHODS: Medical records of all patients diagnosed with presumed bacterial corneal ulcers seen at the Cornea Service, Wills Eye Institute, between January 1, 2004, and December 31, 2007, were retrospectively reviewed. RESULTS: Five hundred seven corneal ulcers were identified. Of these, 223 (43.9%) were contact lens (CL) related and 284 (56.1%) were not CL related. The proportion of CLRU showed a significant increase over time (P = 0.003), with significantly greater percentage of CLRU in 2006 and 2007 compared with 2004 (P = 0.004 and P = 0.005, respectively). One hundred thirty-one (58.7%) of the 223 CLRU patients were men. Many CLRUs were vision threatening, with 45.7% (92 of 201) more than 4 mm in size, 36.3% (81 of 223) associated with hypopyon, and 46.4% (103 of 222) central or paracentral in location. Pseudomonas aeruginosa was the most frequent agent isolated in CLRUs, found in 75 (63.0%) of 119 positive cultures. Soft daily-wear frequent replacement lenses were the most common lenses associated with corneal ulcers and were used in 68 (33.5%) of 203 cases. There was a history of overnight wear of CLs in more than half of the cases (121 of 223, 54.3%). Of these, 21 (9.4%) were not approved for overnight wear. CONCLUSIONS: There was a significant increase in the number of cases of presumed bacterial keratitis associated with soft CL wear over the study period from 2004 to 2007 at our institution. The significant increase in CLRU noted from 1996 to 1999 to 1999 to 2002 reported previously seems to have continued between 2004 and 2007.

PURPOSE: To report an infant with inflicted neurotrauma who exhibited bilateral circumferential macular folds. METHODS: Bedside ophthalmic examination and fundus photography using RetCam-II (Clarity Medical Systems, Pleasanton, CA). RESULTS: Both pupils were miotic and nonreactive. External and anterior segments showed no abnormality. The fundus showed bilateral diffuse multilaminar retinal, subhyaloid, and vitreous hemorrhages. Distinctive macular folds were noted bilaterally. CONCLUSION: Circumferential macular folds are most commonly found in abused infants, although it has been suggested that they may be associated with Terson syndrome and severe crush injury.

PURPOSE: Corneal collagen cross-linking through UVA-riboflavin photochemistry (UVAR) has been shown to be an effective treatment for keratoconus and related keratectasias. In recent studies using sclera, the authors observed that short-chain aliphatic beta-nitro alcohols can cross-link collagenous tissue under physiologic conditions. Thus, this study was undertaken to evaluate these agents as potential pharmacologic alternatives to UVAR. METHODS: Porcine corneal strips (8 x 4 mm) and corneoscleral complexes were cross-linked using 1 to 100 mM 2-nitroethanol (2ne), 2-nitro-1-propanol (2nprop), and 3-nitro-2-pentanol (3n2pent) at pH 7.4, 34 degrees C. Cross-linking by UVAR was carried out for comparison. Thermal shrinkage temperature analysis was used to evaluate cross-linking effects, and changes in corneal light transmission were determined with a fiber-optic spectrophotometer. RESULTS: At 10 and 100 mM for 96 hours, initial shrinkage temperature (T(i)) was shifted by 3.3 degrees C (P < 0.001) and 9.8 degrees C (P < 0.001) for 2ne, 2.9 degrees C (P = 0.008) and 4.9 degrees C (P < 0.001) for 2nprop, and 3.8 degrees C (P = 0.003) and 4.9 degrees C (P < 0.001) for 3n2pent. Reacting at 1 mM through daily exchange of fluid over 7 days shifted T(i) by 3.8 degrees C (P < 0.001), 4.4 degrees C (P = 0.002), and 3.2 degrees C (P = 0.005), for 2ne, 2nprop, and 3n2pent, respectively. These shifts were greater than cross-linking using UVAR (T(i) = 1.9 degrees C; P = 0.012). In the blue light region (400-500 nm), transmission was decreased by 5.6% (P = 0.003), 2.1% (P = 0.260), and 0% (P = 0.428) for 2ne, 2nprop, and 3n2pent, respectively. CONCLUSIONS: beta-Nitro alcohols can induce corneal cross-linking in vitro better than the UVAR technique and can induce negligible effects on light transmission. These early results suggest that such compounds could be used as topical stiffening agents for keratoconus and related disorders

Implanting glaucoma tubes through the pars plana in the setting of a corneal transplant is becoming more common, and there are unique problems associated with such a procedure. A 42-year-old man with multiple previous eye surgeries presented with a nonfunctioning pars plana glaucoma tube. There was no view to the tube tip, but it was presumed to be clogged with fibrin. Intravitreal tissue plasminogen activator (tPA) was injected through the pars plana which resulted in intraocular pressure control without further surgery. This new application of intravitreal tPA has not been reported previously. Future research should investigate the optimal effective and safe dose of intravitreal tPA injection to relieve such occlusions

The success of riboflavin photochemical cross-linking of the cornea in treating keratoconus and post-surgical keratectasia has prompted interest in cross-linking scleral tissue with a potential application to stabilize myopic progression. Applying an UVA light source to the sclera is difficult, particularly in the posterior region. An alternate pharmacologic approach to scleral cross-linking may be possible. The present study was undertaken in order to identify nitrite related compounds capable of inducing scleral tissue cross-linking and to gain information regarding the possible chemical mechanisms involved. 8x4 mm strips of porcine and human sclera were incubated in various concentrations of nitrite related agents (1-100mM) at 37 degrees C. pH 7.4 was used for all experiments except those involving NaNO(2). Following a 24-96 h incubation period, the samples were tested for cross-linking effects using thermal shrinkage temperature (T(s)) analysis. Several compounds were studied including NaNO(2), 2-nitroethanol, 2-nitro-1-propanol, 3-nitro-2-pentanol, 2-nitrophenol, 2-nitroethane, 2-aminoethanol, isopentyl nitrite, DPTA/NO, DETA/NO, and urea, a nitrous acid trap. The results indicate that short chain aliphatic beta-nitro alcohols (2-nitroethanol, 2-nitro-1-propanol, and 3-nitro-2-pentanol) are particularly effective cross-linking agents at pH 7.4, showing both time and concentration dependent effects. Furthermore, nitrosation does not appear to induce tissue cross-linking. In conclusion, aliphatic beta-nitro alcohols can cross-link scleral tissue at physiologic pH and temperature. Since beta-nitro alcohols are known to have reasonable toxicity profiles, these agents could find utility as pharmacologic cross-linking agents for scleral thinning disease

PURPOSE: To compare the accuracy of the potential acuity meter (PAM) and the illuminated near card (INC) in patients undergoing phacoemulsification. METHODS: During presurgical evaluations, both PAM and INC were tested on each study patient following dilation. Patients then rated the subjective ease of use of each test. Best spectacle-corrected visual acuity (BSCVA) was recorded at 4 and 12 weeks postoperatively. McNemar's chi(2) test for paired associations was used to analyse categorical data; paired t-tests were used for continuous variables. RESULTS: Overall, the INC was more likely than the PAM to predict BSCVA within one Snellen line (P=0.002), but this difference decreased for accuracy within two lines. The PAM predicted BSCVA within one line in 87 (70.7%) eyes, as compared to 102 (82.9%) eyes by the INC. The PAM was accurate within two lines in 109 (88.6%) eyes; the INC was accurate in 115 (93.5%) eyes. The PAM was more likely to underpredict potential acuity (P<0.001), while the INC was more likely to overpredict (P=0.004) or give exact predictions of BSCVA (P<0.001). Accuracy of the INC declined in eyes with macular comorbidity. The PAM and INC were rated as 'easy' tests by 54 (45.4%) and 93 (78.2%) patients, respectively. CONCLUSIONS: Both the PAM and the INC were useful for predicting BSCVA after phacoemulsification, but the PAM was more likely to underestimate potential acuity. The INC was easier for patients to use, and had better accuracy than the PAM in patients without macular comorbidity, but was more likely to overestimate potential acuity

AIM: To study possible causes of an outbreak of severe endophthalmitis after planned extracapsular cataract surgery in Medan, Indonesia. METHODS: In a 3 week period in November 2001, 17 of 43 patients developed signs of endophthalmitis after planned extracapsular cataract surgery. A search for possible causes was undertaken 4 months later. RESULTS: In autoclaved stored distilled water used to dissolve acetylcholine (used in 16 of 17 patients with endophthalmitis) a high amount of endotoxin was detected in a human blood essay, as well as a small number of non-typeable Pseudomonas spp. CONCLUSIONS: These findings suggest that distilled water used as solvent for acetylcholine was responsible for this outbreak of endophthalmitis. As a consequence, we now rely on solvents that are regularly checked for impurities such as an intravenous infusion fluid, rather than on vials with distilled water that is presumed to be sterile and kept for some time

PURPOSE: To compare the central corneal thickness (CCT) measurements obtained with noncontact optical low-coherence reflectometry (OLCR) and ultrasound (US) pachymetry. DESIGN: Prospective, comparative observational study. METHODS: Three sequential ultrasonic measurements and a set of five OLCR scans of 52 eyes of 26 healthy subjects were recorded. Noncontact measurement was repeated five minutes after anesthetic drop instillation. RESULTS: Mean CCT values for noncontact OLCR and US pachymetry were 544.03 microm and 548.66 microm, respectively, with mean SDs of 0.97 microm and 4.63 microm, respectively. Noncontact OLCR measured on average 4.64 microm less than US pachymetry (95% confidence interval -7.56 to -1.72; P = .003). The OLCR measured 1.68 microm less than US pachymetry in the thinner cornea group (< or =548.7 microm, n = 24) and 7.48 mum less in the thicker group (n = 25). This difference was statistically significant (P = .04). CONCLUSIONS: There was agreement between the two pachymetric measurements. Noncontact OLCR appeared to measure slightly smaller than US pachymetry

PURPOSE: To report a case of accommodative spasm following laser-assisted in situ keratomileusis (LASIK). DESIGN: Observational case report. METHODS: Ophthalmic examination including manifest and cycloplegic refraction to assist in diagnosis. RESULTS: Two months following LASIK surgery, a 41-year-old healthy woman complained of intolerable headaches that had interfered with her daily activities. The patient sought medical consultation, and an MRI of the brain was normal. Best-corrected visual acuity (BCVA) was 20/20 and 20/25 with manifest refraction of -2.25 -0.50 x 170 and plano in the right and the left eye, respectively. Cycloplegic refraction was plano in the right and +0.75 sphere in the left eye, and she was corrected to 20/20 bilaterally. After being treated with cyclopentolate 1% one drop at bedtime to each eye for approximately six weeks, the headache completely resolved. CONCLUSIONS: Accommodative spasm should be considered in patients undergoing LASIK surgery complicated with fluctuating refraction of uncertain causes