Bitoric ablation appears to be safer, more effective and more tissue-sparing than the standard treatment (monotoric treatment) to correct mixed astigmatism, say investigators in Spain.
Thirty eyes of 15 patients with mixed astigmatism were enrolled in this comparative consecutive study. In each patient, one eye was treated with bitoric ablation (Group 1) and the other eye with monotoric ablation (Group 2). Decision on treatment was randomized, and all patients were operated on by the same surgeon. All completed a six-month follow up.
Investigators found a statistically significant improvement in the mean UCVA (P<.0001), the mean spherical equivalent (SE) (P=.04), and the mean refractive cylinder (P<.0001) in Group 1 and in the mean refractive cylinder (P=.01) in Group 2. Better results were ob-tained in the mean incremental change in UCVA, BCVA, SE and refractive cylinder in Group 1.
(J Cataract Refract Surg 2003;29:1889-1895)
Hassaballa M, Ayala MJ, Alio JL
Link Between Glaucoma and Sleep Apnea Unlikely
Despite previous reports of an association between glaucoma and sleep apnea syndrome, a research team in Israel found the prevalence of glaucoma in SAS patients to be similar to that in the general Caucasian population.
Researchers enrolled 228 patients with confirmed SAS based on polysomnographic evaluation in this cross-sectional study. Sleep studies determined the respiratory disturbance index (RDI) during night sleep, while ocular examination included intraocular pressure measurement, optic disk evaluation and Humphrey visual field examination. An RDI>10 indicated sleep apnea syndrome, with a score of 10 to 19 graded as mild, 20 to 39 moderate, and >40, severe. Open-angle glaucoma was diagnosed when a glaucomatous visual-field defect matched the optic disk changes, irrespective of IOP levels.
Results pointed to mild SAS (RDI=15±3) (mean ± standard deviation) in 19 participants, moderate SAS (RDI=28±5) in 129 patients, and severe SAS (RDI=54±11) in 80 patients. Of these patients, primary open-angle glaucoma was found in five (one mild, three moderate, one severe). This represents a prevalence of two percent, and a 95 percent confidence interval of 0.7 percent to 5 percent, which overlaps the expected prevalence (1.7 percent to 3 percent) in the Caucasian population over the age of 40.
There was no association between RDI and the presence of glaucoma
(P=0.56). The BMI-adjusted correlation between RDI and the presence of glaucoma was also not significant (P=0.47).
(Am J Ophthalmol 2003;136:1093-1096)
Geyer O, Cohen N, Segev E, Rath E, Melamud L, Peled R, Lavie P
Retinal Vascular Characteristics of Diabetics
The Wisconsin Epidemiologic Study of Diabetic Retinopathy documented the frequency and distribution of retinal vascular characteristics and their relationships to various factors in persons with type 1 diabetes.
The population-based study enrolled 996 persons diagnosed with diabetes before age 30 and taking insulin. Patients from an 11-county area in south-central Wisconsin participated in the baseline examination from 1980 to 1982. In addition, 225 people without diabetes participated.
Evaluation included retinal photographs of seven standard fields. Researchers performed lightbox grading to determine arteriovenous (A/V) nicking and focal retinal arteriolar narrowing. Computer-assisted grading was performed from a digitized image of field 1 to determine central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and the arteriole-to-venule ratio (AVR).
From multivariate analyses, researchers determined that retinopathy severity, mean arterial blood pressure, presence of gross proteinuria, glycosylated hemoglobin and history of cardiovascular disease were associated with CRAE.
CRVE was associated with retinopathy severity, age, mean arterial blood pressure, duration of diabetes, glycosylated hemoglobin level and body mass index. With the ex-ception of glycosylated hemoglobin level, similar factors were associated with the arteriole-to-venule ratio.
Age and retinopathy severity were associated with focal retinal arteriolar narrowing and A/V nicking, respectively. In those age 18 and under, smoking was associated with CRAE, CRVE, and A/V nicking, but not with AVR or focal arteriolar narrowing.
Klein R, Klein B, Moss S, Wong T, Hubbard L, Cruickshanks K, Palta M