Clear Lens Extraction for High Myopia Yields High Satisfaction Rate Over Long Term in Italian Study

By Roibeard O'hEineachain

CANNES-In patients with high myopia, clear lens extraction and IOL implantation can provide a highly satisfactory outcome over the long term and probably does not increase the risk of retinal detachment in uncomplicated cases, according to Roberto Bellucci, MD, who will be presenting the results of a 10-year follow-up study here at the Winter Refractive Meeting of the ESCRS.

In 30 eyes of 22 patients who underwent CLE and IOL implantation for myopia ranging from -8 to -24 D in the years 1988-1990, the final refraction ranged from 0-12 D and the mean best-corrected visual acuity improved from 20/40 to 20/30, with the exception of one eye which had retinal detachment 12 months after surgery and eventually lost useful vision, Dr. Bellucci, Ophthalmic Unit, Hospital of Desenzano, Italy told EuroTimes in an interview.

Changed Their Lives
"We interviewed those patients over the last couple of weeks and all of them except the patient with retinal detachment told me that I changed their lives and that they would gladly do it all over again. They got a new style of life, an improved social position, a better ability to work, and a better ability to relate to other people."

Dr. Bellucci noted that iseikonia rather than emmetropia was the goal in about half of the eyes, and as a consequence in 10 eyes the myopia remained at -3D or more in 10 patients and between -0.5 D and -3.0D in five eyes. In the other eyes, the spherical equivalent was between plano and - 0.5 D. Furthermore, since all surgeries were extra-capsular, many eyes had against-the-rule astigmatism up to -3 D.

"Many of these patients wear optical correction for residual errors but some of them do not because highly myopic patients can do well without correction of small post-operative refractive errors. The reason is that they experience such a huge increase in visual acuity that they can do well without the correction of one or two dioptres of myopia.

Myopic Progression Halted
"What we are also observing is that in patients younger than 30 years the progression of myopia was stopped by surgery. Of course we can not measure the axial length of the eye any more but we can measure refraction and they were +/- 0.5 or 1.0 D and had the same spectacle correction 10 years after surgery."

Patients in the study included 15 men and 7 women with a mean age of 36 years (ranged 19-55 years). Their mean pre-operative spherical equivalent was 15.1 D. All underwent extra-capsular cataract extraction and implantation of a 6.5 mm or 7.0 mm PMMA IOL.

The only surgical complications were three posterior capsule ruptures which did not adversely affect the visual outcome. During the first post-operative year, a retinal detachment occurred in one of three eyes which had undergone prophylactic argon laser photocoagulation prior to surgery for pre-existing retinal degeneration. After several years a further three eyes developed pseudophakic glaucoma.

"The rate of retinal detachment observed in this study (3.3%) was not that different from what you would expect in 30 highly myopic eyes over ten years. However, the timing of the detachment that did occur strongly suggests that it was elicited by surgery itself or by the argon laser prophylactic treatment which could impair the vitreo-retinal junction, leading to an increase in traction by the vitreous over the retina.

"As regards glaucoma, it is a common opinion among ophthalmologists in Italy that if a myopic eye undergoes lens surgery this eye will be more prone to develop glaucoma over a period of years. However, we have no theory to explain why this should be. In this study, for example, the eyes which developed glaucoma were completely quiet and had no flare or distortion of the anterior segment. Furthermore, the phenomenon is the opposite of what occurs in non-myopic eyes, where lens extraction typically brings about a 2-3 mm Hg decrease in IOP."

Useful for High Hyperopia
Dr. Bellucci told EuroTimes that CLE is also useful in the treatment of older patients with high hyperopia. The procedure not only provides an improvement of distance vision but also eliminates the risk of angle-closure glaucoma. Furthermore, the risk of retinal detachment in hyperopic eyes is small, as is the risk of choroidal effusion when phaco is used.

"I prefer LASIK in the young hyperopic patients but I do CLE in patients who are 40 years or older when presbyopia starts to set in and there is an increased risk of angle-closure glaucoma. Angle-closure glaucoma is almost exclusive to highly hyperopic eyes, many of which have a shallow anterior chamber and develop angle closure glaucoma as they get older, due to the enlargement of the crystalline lens. In fact, I would recommend lens surgery regardless of their vision just to relieve the risk of angle-closure glaucoma and to obviate the need for cataract surgery later on."

Dr. Bellucci noted that in highly myopic patients he currently reserves CLE for older patients and prefers to use phakic IOLs in younger patients in order to preserve accommodation. The main contra-indications for the procedure are retinal degeneration and unrealistic expectations in patients whose macula is damaged by the myopic process.

"Once accommodation is not present, it may be that CLE is a better approach than phakic IOLs. The procedure allows an increased visual acuity and avoids the likely formation of cataracts. I removed two phakic IOLs in patients a few months after implantation because of cataracts so I have changed my opinion and now I only implant phakic IOLs in younger patients."

Dr. Bellucci's co-author is Franco Spedale, MD.