Lens surgery (cataract and refractive lens exchange) and retinal detachment risk in myopes: still an issue?

A frequent point of debate between refractive and retinal surgeons is the risk of pseudophakic retinal detachment (RD) in highly myopic eyes, defined as eyes with an axial length greater than 26 mm (sometimes even exceeding 30 mm) and usually with a spherical equivalent superior to e6.00 D. This degree of myopia is mostly associated with degenerative changes that involve sclera, choroid, retina and vitreous. Today, refractive lens exchange (RLE) is frequently proposed as a refractive surgical procedure for the correction of high myopia in presbyopic middle-aged myopes, and cataract surgery is performed at earlier ages. However, it is important to determine the risk of RD after both RLE (whether cataractous or a clear lens) and phakic intraocular lenses (whether anterior or posterior chamber) especially in highly myopic eyes. But do we have the evidence about this important issue to inform our patients and to alert ourselves to advise our patients adequately? Every ophthalmic surgeon remembers the stressing experience of a relatively young myopic patient suffering RD following an RLE. Even today and with the progress in vitreoretinal surgery, RD is not always followed by a full visual recovery, and severe visual loss is the endpoint of many patients with RD. The risk of retinal detachment in highly myopic patients is mainly due to two possible causes: a higher incidence of predisposing retinal lesions in myopic eyes compared with the general population and the hypothesis that LE might induce several iatrogenic factors that will increase the incidence of retinal tears, especially promoting vitreous changes postoperatively. The literature on this issue is frequently unclear. Previous studies reported a higher incidence of RD in unoperated highly myopic eyes compared with non-myopic eyes (whether emmetropic or hypermetropic). 2 These studies reported a risk of RD ranging between 0.71% and 3.2%. 2 Previously published reports studied highly myopic eyes with a spherical equivalent (SE) > 6.0 D and included 1000 eyes. The annual incidence was 0.015% in eyes with myopia #4.75 D, 0.07% in myopic eyes ranging between 5.0 D and 9.75 D, and 0.075% in eyes with myopia >10 D. In myopes of up to 15 D, the risk of developing RD increases 15-fold compared with the general population. This risk increases 110-fold in highly myopic patients > 15 D when compared with the general population. Burton reported that high myopes > 5.0 D with retinal degeneration are prone to an extraordinary risk of developing RD, especially with a long life expectancy. The risk of developing RD during the second, third or fourth decade of life is very high in such patients, mainly owing to atrophic retinal holes. However, Burton did not provide any results on severe myopia owing to high axial length. Analysing previous reports studying the incidence of RD after lens removal in highly myopic patients is difficult. Previous studies have reported on differing populations using different surgical techniques (extracapsular cataract extraction (ECCE) and phacoemulsification), whereas others compared the incidence after clear and cataractous lens extraction. Modern phacoemulsification seems to be safer than ECCE, and cataract removal is performed at older ages than RLE, so phacoemuslification in older ages in the high myope probably defines a different risk group, which creates a significant bias in the analysis of RD risk. Significantly, the mean follow-up, mean SE and mean age varied greatly in these published reports. Previous studies reported an incidence of 2.10% in 190 myopic eyes after clear lens exchange (CLE) ‘phacoemulsification’ after a mean follow-up of 4.78 years. Other studies reported an incidence of 4.0% in 25 high myopic eyes (>12.0 D) and 3.2% in 62 eyes. However, a study that included 930 highly myopic eyes with an SE ranging from 30.0 D to 15.0 D reported an incidence of 8% with a mean age of 62.5% years and mean follow-up of 36 months. In another study with longer mean follow-up of 62.3 months and mean axial length of 30.22 mm the reported incidence of RD was 1.3% but this study involved a smaller cohort (73 eyes) and without intraocular lens implantation. Other authors have reported a RD incidence up to 8.1% after 7 years of follow-up. Again, differences in risk apparently exist when considering whether cataract removal or RLE is the indication of the surgery related to vitreous changes occurring in the younger patients. We cannot compare RD incidence after CLE with cataract extraction in high myopes (as the incidence is lower after cataract extraction). In young patients, especially with high life expectancies, CLE can induce vitreous changes and increase the traction on the retina, which would not be expected to occur in older patients after cataract extraction. To further understand the problem of RD following RLE and cataract removal in the myope, we conducted a retrospective study in which we analysed RD incidence in 439 high myopic eyes of 274 patients after lens surgery (CLE and cataract) with a mean age of 62.2611.7 years (ranging from 21 to 90 years), with a mean follow-up of 61.5629.6 months (range from 2 to 147 months) with different surgeons. All highly myopic eyes with an axial length of over 26 mm and spherical equivalent $ 6.00 D were included. Eyes previously operated for RD or other intraocular surgeries (three eyes) were excluded from this study. The mean outcome measures were the occurrence of RD, age, axial length, operative complications (vitreous loss) posterior capsular opacification and Nd:YAG capsulotomy, in addition to postoperative BSCVA and spherical equivalent. Patients were divided into two groups according to age at the time of surgery, Group 1 patients of 50 years or younger (82 eyes) and Group 2 patients of over 50 years of age (357 eyes). Eyes were also divided according to axial Department of Ophthalmology, Miguel Hernández University School of Medicine and VISSUMdInstituto Oftalmológico de Alicante, Department of Cornea and Refractive Surgery, Alicante, Spain