Simple test predicts cataract surgery outcome

By Roibeard O'hEineachain

BRUSSELS - A simple preoperative macular function test can provide surgeons with an accurate prediction of a cataract patient's visual outcome after surgery, according to Jérôme C Vryghem MD.

The test involves having the patients read a Parinaud chart at a distance of about 12 cm with a hyper-addition lens of +8 D over and above their long distance correction. The distance at which the text is held is critical and patients must adjust this distance for themselves. A Heine bonoscope was used to closely illuminate the lines on the near card. The chart includes only numbers with either the Parinaud 1 or LEA Optotype 10/10, explained Dr Vryghem, Clinique St-Jean, Brussels.

"This macular function test is easy to perform. It requires only limited material and has a score that is easy to record. It also has a high positive predictive value. In cases of senile macular changes, it allows the surgeon to take a correct decision whether to operate or not," he said.

Retrospective trial
Dr Vryghem and his associates Dr H Van Cleynenbreugel and Dr K Leroux conducted a retrospective study of 400 uncomplicated consecutive cataract procedures performed by a single surgeon from September 2000 to February 2001. The patients included 130 men and 270 women with a mean age of 77 years. The mean preoperative BCVA was 20/50. None of the patients had previous eye surgery or trauma and none had any known paracentral scotoma or corneal oedema.

Overall, 363 eyes (90.7%) could read Parinaud I in the preoperative test. Among these eyes, final BCVA was better than or equal to 20/25 in 338 (93.1%) and better than or equal to 20/30 in 365 (98.1%). Among 37 eyes that were not able to read Parinaud 1 preoperatively and yet attained 20/25 or better postoperatively, 25 presented with dense nuclear or subcapsular cataract. Among seven eyes that were able to read Parinaud 1 preoperatively but did not achieve a BCVA 20/30 or better postoperatively, four were known to be amblyopic.

The results of this study suggest that this simple macular function test has a positive predictive value of 93.1 % to predict a visual outcome of equal to or better than 20/25 after uncomplicated cataract surgery with a sensitivity of 93.1 % and a specificity of 32.4 %.

The negative predictive value is 32.4 %. If a BCVA of 20/30 or better is considered, the positive predictive value is 98.1%. If amblyopic eyes are excluded from the total group, the positive predictive value of the test is even better (99.2% reached a postoperative BCVA equal or better than 20/30). In patients with dense cataracts, where Parinaud 1 cannot be read, it has no predictive value. In patients with amblyopia where Parinaud 1 can be read, it is too optimistic.

Dr Vryghem presented his findings at the XIX Congress of the ESCRS.

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