Visual-evoked potentials: assessment of retrobulbar and peribulbar anesthesia.

PURPOSE: To assess the effects of retrobulbar and peribulbar anesthesia on nerve function as detected by visual-evoked potentials (VEPs). SETTING: University hospital in southern Brazil. METHODS: In a prospective study, 7 patients had peribulbar anesthesia and 9 had retrobulbar anesthesia for extracapsular cataract extraction. Visual-evoked potentials with pattern reversal and flash stimulation were performed at least 1 month before and 1 month after surgery. Study participants did not have ocular pathology other than cataract. The Lens Classification System III was used to grade the opacities before surgery. RESULTS: No significant difference was found between preoperative and postoperative evaluations in VEP flash and pattern-reversal amplitude and latency in either group (P >.05). Postoperative amplitude and latency was not significantly different between the peribulbar and retrobulbar groups. Two cases in the peribulbar group had altered wave morphology without clinical manifestation postoperatively. All patients had a final best spectacle-corrected visual acuity of 20/20. CONCLUSION: Block anesthetic procedures were safely used in cataract surgery, with no clinical sequelae to the optic nerve.

Potential acuity meter accuracy in cataract patients.

PURPOSE: To determine potential acuity meter (PAM) accuracy in patients with cataract as the only ocular disease. SETTING: Hospital de Clínicas de Porto Alegre, Brazil. METHODS: This prospective study comprised 74 eyes with cataract. Patients with other ocular pathology diagnosed before or after surgery, as well as those with complicated surgeries, were excluded. All patients had PAM evaluation before surgery; these results were compared to the final postoperative visual acuity. Patients were divided into 4 cataract groups based on the Lens Opacity Classification System II: Group 1, early cataracts (nuclear opalescence [NO] 1 and/or posterior subcapsular cataracts [P] 1 and/or cortical opacity [C] < 2); Group 2, definite cataracts (NO2 and/or C2, with or without P1); Group 3, posterior cataracts (P2 or P3); Group 4, mature cataracts (N3 and/or C > or = 3, with or without P1). The PAM result was considered accurate if it was within 2 lines of the postoperative best spectacle-corrected visual acuity (BSCVA) 3 months after surgery. RESULTS: All patients had a BSCVA of 20/20. Accuracy of the PAM was 58.3% in Group 1, 50.0% in Group 2, 27.8% in Group 3, and 6.7% in Group 4 (P =.000 017). Patient age did not influence the results. CONCLUSIONS: The PAM may be used as a complementary tool in evaluating early and nondense cataracts; however, patients should not be excluded as candidates for cataract surgery based solely on PAM results.