Significant improvement in BCVA in most patients with retinitis pigmentosa following cataract surgery: AJO
Retinitis pigmentosa (RP) is a collective term for inherited retinal dystrophies that are characterized by degeneration of primarily rod photoreceptors, followed by loss of cone photoreceptors. As result of photoreceptor degeneration, patients may experience symptoms of night blindness, concentric loss of peripheral visual fields, and ultimately, central vision loss. There is great variability in patients with RP with regards to their disease onset, severity, progression and their potential complications. The most common anterior segment complication described in RP is cataract, with the most common type being posterior subcapsular cataract (PSC).
Cataract develops at a relatively younger age in patients with RP compared to patients with age-related cataract, which is presumably caused by an early inflammation response invoked by RP. Depending on the severity and morphology of cataract, loss of visual function is accompanied or preceded by visual disturbances, including symptoms of glare, photophobia and decreased contrast sensitivity, among others. In patients with RP, cataracts may cause disproportionate functional symptoms due to the presence of both lenticular and retinal pathology.
Surgical removal of cataract, followed by the implantation of an intraocular lens (IOL), is the primary treatment to improve visual function and/or to alleviate perceived visual disturbances. In absence of ocular comorbidities and surgical complications, cataract surgery leads to significant improvements in objective and subjective visual function.
However, in patients with RP, the visual prognosis following cataract surgery is uncertain, as gradual loss of visual function can be attributed either to the development of lens opacities or to the ongoing retinal degeneration process by RP. Furthermore, patients with RP are predisposed to intraoperative phototoxic retinal damage, cystoid macular edema (CME), and weakened lens zonules, which may negatively influence the visual prognosis and increase the risk of surgical complications. Postoperatively, higher incidences of posterior capsular opacifications (PCO) and anterior capsular contraction have also been reported in RP, which may also impact the visual outcome if left untreated.
Despite the uncertain visual prognosis and surgical risks, cataract surgery should still be considered in patients with RP. The study by Xuan-Thanh-An Nguyen et al aimed to evaluate the visual outcome of cataract surgery using retrospective non-comparative clinical study. They reported the objective and subjective visual benefit of cataract surgery, the impact of risk factors on the visual outcome, and the incidence of intraoperative and postoperative complications. Using this knowledge, recommendations and considerations will be provided that may aid the counselling and clinical management of cataract in patients with RP. Preoperative, intraoperative and postoperative data of patients with RP undergoing cataract surgery were collected from several expertise centers across Europe
In total, 295 eyes of 225 patients were included in the study.
Following surgery, best-corrected visual acuity (BCVA) improved significantly from 1.03 to 0.81 logMAR (i.e. 20/214 to 20/129 Snellen) in the first treated eye (-0.22 logMAR; p < 0.001), and from 0.80 to 0.56 logMAR (i.e. 20/126 to 20/73 Snellen) in the second treated eye (-0.24 logMAR; p < 0.001).
Marked BCVA improvements (postoperative change in BCVA of ≥ 0.3 logMAR) were observed in 87 out of 226 patients (39%). Greater odds for marked visual improvements were observed in patients with moderate visual impairment or worse.
The most common complications were zonular dialysis (n = 15; 5%), and (exacerbation of) cystoid macular edema (n = 14; 5%), respectively. Postoperative posterior capsular opacifications were present in 111 out of 295 (38%) eyes.
This study demonstrates that cataract surgery in patients with RP leads to significant improvements in visual acuity, with more than half of the eyes included having better BCVA postoperatively than preoperatively. On average, BCVA improvements of 0.22-0.24 logMAR were observed, which is comparable to a 2- to 3-line BCVA increase measured on Snellen charts.
Despite the impact of RP on visual acuity, authors found that marked BCVA improvements (greater than 0.3 logMAR) were also possible in this cohort following cataract surgery. They found that preoperative BCVA was a predictor for marked BCVA improvements, as groups with a BCVA of 20/200-20/67 Snellen (i.e. moderate visual impairment) and 20/200 or worse (i.e. severe impairment/blindness) had better odds of achieving marked BCVA improvements than patients with a BCVA of 20/67 or better (i.e. mild/no visual impairment). This would be expected, as patients preserved visual acuities are limited in their BCVA improvements due to a ceiling effect. Another possible and additional explanation is that patients with poor preoperative BCVA have more severe vision-impairing cataracts, which, in turn, yields higher gains in BCVA following surgery.
In conclusion, this study suggests that cataract surgery leads to significant improvements in BCVA in the majority of patients with RP, with baseline BCVA being a potential predictive factor. Patients may experience subjective visual improvement, irrespective of their visual outcome. Surgeons should be aware of the high prevalence of zonular weakness and CME, which may warrant additional preparation. A high rate of PCO is also present, which requires early treatment with laser posterior capsulotomy. Further studies should include SD-OCT imaging, and the use of patient-reported outcome measures, as they are potentially important parameters for the evaluation of visual outcome.
Source: Xuan-Thanh-An Nguyen , Alberta A.H.J. Thiadens , Marta Fiocco et al, Outcome of cataract surgery in patients with retinitis pigmentosa, American Journal of Ophthalmology (2022),
