Karim F. Damji

Selective laser trabeculoplasty v argon laser trabeculoplasty: a prospective randomised clinical trial.

AIMS To compare the effectiveness of selective laser trabeculoplasty (SLT, a 532 nm Nd:YAG laser) with argon laser trabeculoplasty (ALT) in lowering the intraocular pressure (IOP) in patients with medically uncontrolled open angle glaucoma. METHODS A prospective randomised clinical trial was designed. Patients were randomised to treatment with either SLT or ALT and were evaluated at 1 hour, 1 week, 1, 3, and 6 months post-laser. RESULTS There were 18 eyes in each group. Baseline characteristics were similar in both groups. In the SLT group the mean IOP at baseline, 1, 3, and 6 months was 22.8 (SD 3.0), 20.1 (4.6), 19.3 (6.0), and 17.8 (4.8) mm Hg, respectively. In the ALT group, the mean IOP at baseline, 1, 3, and 6 months was 22.5 (3.6), 19.5 (4.7), 19.6 (5.6), and 17.7 (3.3) mm Hg, respectively. There was a greater anterior chamber reaction, 1 hour after SLT v ALT (p< 0.01). Patients with previous failed ALT had a better reduction in IOP with SLT than with repeat ALT (6.8 (2.4) v 3.6 (1.8) mm Hg; p = 0.01). CONCLUSION SLT appears to be equivalent to ALT in lowering IOP during the first 6 months after treatment. There is a slightly greater anterior chamber reaction 1 hour after SLT. Patients with previous failed ALT had a significantly greater drop in IOP when treated with SLT vALT. These results need to be confirmed with a larger sample size.

Selective laser trabeculoplasty versus argon laser trabeculoplasty: results from a 1-year randomised clinical trial

Aims: To compare selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT), in terms of intraocular pressure (IOP) lowering, in patients with open-angle glaucoma. Methods: 176 eyes of 152 patients were enrolled in this study, 89 in the SLT and 87 in the ALT groups. Patients were randomised to receive either SLT or ALT treatment to 180° of the trabecular meshwork. Patients were followed up to 12 months after treatment. The main outcome measured was IOP lowering at 12 months after treatment, compared between the SLT and ALT groups. Results: No significant difference (p = 0.846) was found in mean decrease in IOP between the SLT (5.86 mm Hg) and ALT (6.04 mm Hg) groups at 1 year or at any other time points, nor were there any significant differences in the rate of early or late complications between the two groups. Conclusions: SLT is equivalent to ALT in terms of IOP lowering at 1 year, and is a safe and effective procedure for patients with open-angle glaucoma.

Positive correlation between Tono-pen intraocular pressure and central corneal thickness

OBJECTIVE To examine the relationship between intraocular pressure (IOP) readings taken by the Tono-Pen tonometer (Mentor O&O, Norwell, MA) and central corneal thickness (CCT). DESIGN Prospective cross-sectional population study. PARTICIPANTS There were 651 eyes of 332 healthy subjects. MAIN OUTCOME MEASURES A questionnaire was given to each subject requesting information on gender, age, race, and other factors that can influence IOP. The IOP then was measured using the Tono-Pen followed by measurements of CCT using an ultrasonic pachymeter. RESULTS The IOP was found to increase by 2.9 mmHg/100 microns CCT in males and 1.2 mmHg/100 microns in females. For males, CCT was found to be statistically significant in predicting IOP (P < 0.001 in the right and left eyes) and diabetes was of borderline significance (P = 0.012 in the right eye, P = 0.089 in the left eye). For females, CCT was of borderline significance (P = 0.064 in the right eye, P = 0.019 in the left eye). In females, a family history of glaucoma (P = 0.021 in the right eye, P = 0.022 in the left eye) and hypertension (P = 0.010 in the right eye, P = < 0.001 in the left eye) were also significant in the prediction of IOP. Race was found to be a significant predictor of CCT (P < 0.001 in both right and left eyes) for both males and females. CONCLUSION Clinicians should be aware that, as with the Goldmann applanation tonometer, the Tono-Pen has a systematic error in IOP readings caused by its dependence on CCT. Tono-Pen IOP readings are positively correlated to CCT in males and, to a lesser extent, in females as well. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in the diagnosis and management of disorders in which the CCT or IOP readings are outside normal limits.

Baseline IOP predicts selective laser trabeculoplasty success at 1 year post-treatment: results from a randomised clinical trial

Background/aims: The efficacy and safety of selective laser trabeculoplasty (SLT) has been found to be equivalent to argon laser trabeculoplasty (ALT). Since SLT produces significantly less disturbance to the trabecular meshwork and is theoretically more repeatable than ALT, it has potential to replace ALT as the standard procedure to treat medically uncontrolled open angle glaucoma. This study’s objective is to determine factors that predict successful SLT at 1 year post-treatment. Methods: As part of a randomised clinical trial comparing the efficacy and safety of SLT to ALT, data on 72 SLT patients were collected, and successful SLT defined as having an SLT induced intraocular pressure (IOP) reduction of ⩾20% at 1 year post-treatment follow up. Results: 43 out of the 72 patients who had completed their 1 year follow up visit had an IOP reduction of ⩾20% from baseline. No glaucoma risk factors studied predicted successful SLT. The amount of trabecular meshwork pigmentation was not a significant predictor. However, it was discovered that baseline IOP strongly predicted SLT success (odds ratio = 1.16; p = 0.0001). Conclusion: SLT success was significantly predicted by baseline IOP but not by age, sex, other glaucoma risk factors, type of open angle glaucoma, or by degree of trabecular meshwork pigmentation.

Intraocular pressure decrease after phacoemulsification in patients with pseudoexfoliation syndrome.

Purpose: To determine the intraocular pressure (IOP) response to phacoemulsification cataract extraction with posterior chamber intraocular lens (PC IOL) implantation in patients with pseudoexfoliation syndrome. Setting: Eye clinics at the University of Ottawa Eye Institute, Ottawa, Ontario, Canada. Methods: A retrospective cohort study design assigned patients to 1 of 3 subgroups: pseudoexfoliation syndrome (PEX) (n = 21), primary open‐angle glaucoma (POAG) control (n = 23), and cataract control (n = 23). Inclusion criteria consisted of age older than 50 years, open angle by gonioscopy, and a cataract requiring phacoemulsification. The IOP response was determined at intervals up to 18 months. Results: Postoperative IOP changes from baseline in the PEX group were –1.81, –4.52, and –2.31 mm Hg at 3, 6, and 12 months, respectively. The changes in the POAG control group were –2.22, –2.32, and –1.88 mm Hg, respectively, and in the cataract control group, –2.49, +0.45, and +0.28 mm Hg. Patients in the PEX group had a reduction in IOP from baseline at all postoperative measurements. That reduction was significantly greater than in the POAG and cataract control groups at 6 months (P = .012 and P = .002, respectively) and 12 months (P = .001 and P = .050, respectively). Conclusions: Patients with pseudoexfoliation syndrome had a postoperative IOP reduction from baseline at all measurements and a significantly greater reduction than patients in the POAG and cataract control groups at 6 and 12 months. Phacoemulsification cataract surgery with PC IOL implantation may be effective in managing patients with pseudoexfoliation syndrome who have elevated IOP and visually significant cataract but no advanced optic nerve damage.

Ab interno trabeculectomy: Outcomes in exfoliation versus primary open-angle glaucoma

PURPOSE: To compare outcomes in exfoliation glaucoma versus primary open‐angle glaucoma (POAG) after ab interno trabeculectomy alone (Trabectome) or in combination with cataract surgery and intraocular lens (IOL) implantation. SETTING: Trabectome Study Group institutions. DESIGN: Prospective nonrandomized cohort study. METHODS: Outcomes included intraocular pressure (IOP), glaucoma medications, complications, secondary procedures, and success, defined as no secondary surgery and IOP less than 21 mm Hg and a greater than 20% reduction from baseline. RESULTS: In the ab interno trabeculectomy–alone group, the mean preoperative IOP was 29.0 mm Hg ± 7.5 (SD) in exfoliation glaucoma cases and 25.5 ± 7.9 mm Hg in POAG cases (P<.01). At 1 year, the mean decrease in IOP was −12.3 ± 8.0 mm Hg and −7.5 ± 7.4 mm Hg, respectively (P<.01); the secondary procedure rate was 20.9% and 34.9%, respectively (P=.02); and the cumulative probability of success was 79.1% and 62.9%, respectively (P=.004). In the combined ab interno trabeculectomy–IOL group, the mean preoperative IOP was 21.7 ± 8.4 in exfoliation glaucoma cases and 19.9 ± 5.4 mm Hg in POAG cases (P=.06). At 1 year, the mean decrease in IOP was −7.2 ± 7.7 and −4.1 ± 4.6, respectively (P<.01); the secondary procedure rate was 6.7% and 6.1%, respectively (P=.88); and the cumulative probability of success was 86.7% and 91.0% (P=.73), respectively. CONCLUSION: Ab interno trabeculectomy using this new incisional procedure safely lowered IOP to the mid teens, with an overall greater reduction in exfoliation glaucoma and improved success when combined with cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Influence of corneal variables on accuracy of intraocular pressure measurement.

The accurate measurement of intraocular pressure (IOP) is a cornerstone of the diagnosis and management of glaucoma. This article reviews various methods of IOP measurement, summarizes the basic principles involved and the advantages and disadvantages of each technique, and discusses factors, focusi

Disc excavation in dominant optic atrophy Differentiation from normal tension glaucoma

OBJECTIVE In patients with dominant optic atrophy (DOA, Kjer type), excavation of the optic nerve develops, and these patients may be misdiagnosed as having normal tension glaucoma (NTG). This study examined disc morphologic features in patients with DOA and explored features that help distinguish this condition from NTG. DESIGN Noncomparative, observational case series. PARTICIPANTS Patients with DOA who were seen at the Duke University Eye Center between 1987 and 1996 and who had bilateral optic nerve photographs. METHODS Retrospective chart review of the results of visual acuity testing, visual field testing by Goldmann perimetry, color vision testing, intraocular pressure measurement, and observation of bilateral optic nerve photographs. MAIN OUTCOME MEASURES Appearance of the optic disc and peripapillary zone in patients with DOA. RESULTS Nine patients were identified. The mean age at the time of evaluation was 28 years (range, 11-62 years). Most patients had a mild to moderate reduction in visual acuity. Color vision as tested with Hardy-Rand-Rittler plates was reduced (4.0/10 +/- 4.2/10). A cup-to-disc ratio of more than 0.5 was observed in at least one eye of eight patients. A temporal wedge-shaped area of excavation was observed in 14 of the 18 eyes studied. Moderate to severe temporal pallor was observed in all of the eyes. Pallor of the remaining (noncupped) neuroretinal rim was also observed consistently, ranging from mild to moderate. A gray crescent and some degree of peripapillary atrophy were noted in all eyes. CONCLUSIONS Several clinical features, including early age of onset, preferential loss of central vision, sparing of the peripheral fields, pallor of the remaining neuroretinal rim, and a family history of unexplained visual loss or optic atrophy, help to distinguish patients with DOA from those with NTG.

Long term effects on the lowering of intraocular pressure: selective laser or argon laser trabeculoplasty?

OBJECTIVE Selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) are used to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). We report long-term follow-up data comparing SLT to ALT. DESIGN Follow-up of prospective randomized clinical trial. PARTICIPANTS Patients with glaucoma from the practices of three ophthalmologists at the University of Ottawa. METHODS We randomized 176 eyes of 152 patients with uncontrolled IOP on maximal tolerated medical therapy (MTMT, with or without previous ALT) to undergo either SLT or ALT. Data were available for 142 eyes at 3 years, 134 eyes at 4 years, and 120 eyes at 5 years. The primary outcome was change in IOP from pretreatment baseline. RESULTS Comparison of baseline parameters was similar in the two groups. Lowering of IOP were similar at 3 years (SLT -6.7 ± 7.1 vs ALT -6.1 ± 5.1); at 4 years (SLT 7.0 ± 7.7 vs ALT -6.3 ± 5.0); and at 5 years (SLT -7.4 ± 7.3 vs ALT -6.7 ± 6.6). There was no statistically significant change in IOP in either of the two groups. Medication changes were equivalent in each group. A number of interventions were required in both groups, cumulatively, over the 5-year follow-up period (49 SLT and 33 ALT). Survival analysis indicated that the time to 50% failure in each group was approximately 2 years. CONCLUSIONS The IOP-lowering effect of SLT and ALT was similar over 5 years in this group of patients with open-angle glaucoma on MTMT.

Leber's congenital amaurosis with anterior keratoconus in Pakistani families is caused by the Trp278X mutation in the AIPL1 gene on 17p

BACKGROUND Lebers congenital amaurosis (LCA) represents the earliest and severest form of retinal dystrophy leading to congenital blindness. A total of 20% of children attending blind schools have this disease. LCA has a multigenic basis and is proving central to our understanding of the development of the retina. We describe the clinical and molecular genetic features of four inbred pedigrees from neighbouring remote villages in northern Pakistan, in which some of the affected members have concurrent keratoconus. METHODS History-taking and physical and eye examinations were performed in the field. Venipuncture, DNA extraction, studies of linkage to known LCA genes, automated sequencing and polymorphism analyses for haplotype assessments were done. RESULTS We examined 12 affected and 15 unaffected family members. By history, there were an additional nine blind people in the four pedigrees. In each pedigree a consanguineous marriage was evident. We found a homozygous nonsense mutation in the AIPL1 gene, which replaces a tryptophan with a stop codon (Trp278X). The phenotype is severe and variable, despite the common molecular genetic etiology in each family. Affected patients had hand motion to no light perception vision and fundus findings ranging from maculopathy to diffuse pigmentary retinopathy. Three affected members had definite keratoconus, and two were suspects based on mild cone formation in the cornea of at least one eye. INTERPRETATION We have identified four Pakistani families with a severe form of LCA that is associated with severe keratoconus in some affected members. The molecular etiology in all four families is a homozygous nonsense mutation, Trp278X, in the photoreceptor-pineal gene AIPL1. To our knowledge, this is one of the first phenotype-genotype correlations of AIPL1-associated LCA.