M.F. White

Delays in rod-mediated dark adaptation in early age-related maculopathy

OBJECTIVE To determine whether there are disturbances in the rod-mediated kinetics of dark adaptation in early age-related maculopathy (ARM). DESIGN Comparative, observational case series. PARTICIPANTS Twenty older adults with early ARM as defined by one or more large (> 63 microm) drusen, focal hyperpigmentation, or both, but no choroidal neovascularization or geographic atrophy, and 16 adults in the same age range with none of these fundus features. All participants had 20/25 visual acuity or better in the tested eye. METHODS Dark adaptation functions were measured using a modified Humphrey Field Analyzer (Zeiss Humphrey Systems, Dublin, CA) to assess the rate of rod-mediated sensitivity recovery at 12 degrees on the vertical meridian in the inferior visual field after exposure to the equivalent of a 98% bleach. Baseline (prebleach) scotopic sensitivity, visual acuity, contrast sensitivity, and photopic sensitivity were also measured. MAIN OUTCOME MEASURES Rod-cone break; second and third components of rod-mediated dark adaptation; time to baseline sensitivity; and baseline (prebleach) scotopic sensitivity. RESULTS Although their visual acuity was at least 20/25, patients with early ARM on average exhibited deficits in almost all rod-mediated parameters of dark adaptation as compared with age-similar healthy participants. For example, the rod-cone break was delayed approximately 10 minutes in early ARM patients as compared with healthy participants. Age-related maculopathy patients were more likely to fall outside the normal reference range for variables representing dark adaptation kinetics than for steady-state visual functions such as scotopic sensitivity. For example, 85% of ARM patients fell outside the normal reference range in at least one dark adaptation kinetic parameter, whereas only 25% of ARM patients fell outside the normal reference range for steady-state scotopic sensitivity. CONCLUSIONS Rod-mediated kinetic parameters of dark adaptation, which reflect the sensitivity recovery of the visual cycle, are disrupted early in ARM pathogenesis.

Comparison of Hemorrhagic Complications of Warfarin and Clopidogrel Bisulfate in 25-Gauge Vitrectomy versus a Control Group

PURPOSE To estimate the risk of hemorrhagic complications associated with 25-gauge pars plana vitrectomy (PPV) when warfarin (Coumadin; Bristol-Myers Squibb, New York, NY) or clopidogrel (Plavix; Bristol-Myers Squibb) are continued throughout the surgical period, as compared with a control group. DESIGN A single-center, retrospective, cohort study of 289 consecutive patients receiving either warfarin therapy or clopidogrel therapy or neither of those therapies who underwent 25-gauge PPV. PARTICIPANTS Included were 61 patients (64 eyes; 64 PPV procedures) in the warfarin group and 118 (125 eyes; 136 PPV procedures) in the clopidogrel group. Warfarin patients were subdivided into 4 groups by international normalized ratio (INR). A control group included 110 patients (110 eyes; 110 PPV procedures) who were not receiving warfarin or clopidogrel. METHODS Retrospective chart review for which the criteria included: 25-gauge PPV, minimum age of 19 years, warfarin or clopidogrel use, and, if taking warfarin, an INR obtained within 5 days of surgery. MAIN OUTCOME MEASURES Incidence of intraoperative and postoperative hemorrhagic complications. RESULTS The most common indications for anticoagulation therapy included: atrial fibrillation (38%), valvular heart disease (17%), and thromboembolic disease (16%). The most common indications for antiplatelet therapy included: cardiac stent (49%), coronary artery bypass grafting (24%), and history of transient ischemic attack (16%). No patient experienced anesthesia-related hemorrhagic complications resulting from peribulbar or retrobulbar block. Transient vitreous hemorrhage occurred in 1 (1.6%) of 64 PPV procedures in the warfarin group (P = 0.6531), 5 (3.7%) of 136 PPV procedures in the clopidogrel group (P = 1.0), and 4 (3.6%) of 110 PPV procedures in the control group. No choroidal or retrobulbar hemorrhages occurred in any patient. CONCLUSIONS The rate of 25-gauge PPV hemorrhagic complications in patients who underwent systemic anticoagulation or who were receiving platelet inhibitor therapy is extremely low. Given the risks associated with stopping these therapies, the authors recommend that patients continue their current therapeutic regimen without cessation.