Cataract surgery not apparent risk factor for retinal detachment in highly myopic eyes, study finds

The risk profile for retinal detachment following cataract surgery may be identical to the risk profile for idiopathic retinal detachment in highly myopic eyes.

Cataract surgery is not a demonstrated risk factor for retinal detachment in highly myopic eyes, and the risk profiles for postoperative and idiopathic retinal detachment are identical, according to a large-cohort study.

High myopia is a recognized major risk factor for retinal detachment (RD). There may be further risk factors involved, such as genetic predisposition or lattice degeneration. Surgical risk factors, such as cataract surgery, “may exist, but are difficult to demonstrate,” Irmingard Neuhann, MD, said at the World Ophthalmology Congress in Berlin.

Retrospective study

“We performed a retrospective analysis of 2,356 eyes (1,519 consecutive patients) with axial length greater than 27 mm. Postoperative incidence of retinal detachment was approximately 2% over 2 years in 84% of the cases,” Dr. Neuhann said.

Although retrospective, the study is by far the largest available on the topic. The relatively high incidence of RD confirmed the results of the majority of published studies, in which RD rate ranges between 0% and 3.2%. Only two studies, one by Colin and one by Ripandelli, showed different results, “but I don’t think they have a negative influence on this discussion,” Dr. Neuhann said. “However, in order to decide whether this risk rate is elevated by cataract surgery, we need to know the frequency of spontaneous retinal detachment in high myopic eyes.”

No large epidemiological study has ever demonstrated that the retinal detachment rate following cataract surgery is different from that of spontaneous retinal detachment in myopes with comparable axial length.

“All we have is a handful of relatively small studies with a low level of evidence and no reference to [axial length]. A retinal detachment rate between 3.2% and 7.5% is reported, which is indeed a large percentage,” she said.

RD rates independent of surgery

In the study conducted by Dr. Neuhann and colleagues, axial length was also measured in most of the fellow eyes that did not undergo surgery, and the rate of idiopathic retinal detachment (ie, before surgery) in all eyes was evaluated.

“In the eyes with axial length more than 27 mm, we had an idiopathic detachment rate of 4.6%, 114 out of 2,464 eyes. In eyes with axial length of less than 27 mm, detachment rate was 3%, 12 out of 289 eyes. There was a group of eyes in which we did not measure the axial length, and this is a weak point in the rigorousness of our study. However, it might be interesting to know that also in this group, we had 38 cases of retinal detachment in 185 eyes,” Dr. Neuhann said.

What all these studies show, she concluded, is that the frequency of spontaneous retinal detachment in highly myopic eyes is significant.

The study by Dr. Neuhann and colleagues evaluated whether any of the risk factors for idiopathic retinal detachment had an impact on the rate of postoperative retinal detachment.

“We examined several risk factors, but none of them, not even the male sex, was really significant. The only groups that appeared to be correlated with a higher incidence were young patients and patients who had previously undergone laser treatment,” Dr. Neuhann said.

Laser seemed to carry the highest risk. However, these patients were treated during the 1980s and 1990s, when it was common practice to treat visible lesions prophylactically regardless of whether they were symptomatic.

“They were eyes in which you would expect to have a higher rate of retinal detachment anyhow. So, we need to readjust our argument and conclude that younger patients and patients with a predisposition had a higher rate of postop retinal detachment. And this is exactly the same statement that we would make for idiopathic retinal detachment,” Dr. Neuhann said.

“The conclusion of our study was that the risk profile for retinal detachment following cataract surgery is identical to the risk profile for idiopathic retinal detachment in high myopes,” she said.

Highly myopic patients who present for cataract surgery should be told that myopia is a predisposing factor for retinal detachment, but the risk of having retinal detachment following cataract surgery is not greater than the risk that they would have regardless, she said.

“They should not be afraid of having cataract surgery, knowing that it will have no impact on whether retinal detachment occurs or not,” Dr. Neuhann said. “Opening a whole new discussion, cataract surgery may have an influence, however, on the time point of RD, as it may induce earlier posterior vitreous detachment.” – by Michela Cimberle

References:

• Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: seven-year follow-up. Ophthalmol. 1999;106(12):2281-2284.
• Neuhann IM, Neuhann TF, Heimann H, Schmickler S, Gerl RH, Foerster MH. Retinal detachment after phacoemulsification in high myopia: analysis of 2356 cases. J Cataract Refract Surg. 2008;34(10):1644-1657.
• Ripandelli G, Coppé AM, Parisi V, Olzi D, Scassa C, Chiaravalloti A, Stirpe M. Posterior vitreous detachment and retinal detachment after cataract surgery. Ophthalmol. 2007;114(4):692-697.

• Irmingard Neuhann, MD, can be reached at Helene-Weber-Allee 19, 80637 Munich, Germany; +49-89-2594040; fax: +49-89-25940555; e-mail: praxis@neuhann.de.

Joseph Colin

This study reports an incidence of retinal detachment of 2% after a 2-year follow-up of cataract surgery in highly myopic eyes, which would be similar to the rate of spontaneous retinal detachment (RD) in myopes with comparable axial length. This report is very informative, but may be slightly optimistic.

The estimated rate of RD in nonoperated eyes with myopia is not well-defined in the literature: A good prospective epidemiologic study is really missing, and the most frequently cited study by Perkins reports a 0.68% annual rate in myopes over 10 D. Older studies with very high capsulotomy rates have revealed higher rates of RD. Ripandelli et al reported an incidence of 8% of RD in 930 highly myopic operated eyes vs. only 1.2% in control fellow eyes.

There is a consensus that the risk of retinal detachment has decreased with the development of safer lensectomy techniques that avoid anterior chamber fluctuations, and improvement of IOL design has also decreased the incidence of posterior capsule opacification. However, we must remain very cautious when performing clear lensectomy in highly myopic eyes, as this procedure is usually done in much younger patients who might have specific vitreoretinal lesions.

– Joseph Colin, MD
OSN Europe Edition Chairman of the Editorial Board