Reduced frequency of Intravitreal methotrexate injection lowers the risk of Keratopathy in Vitreoretinal lymphoma patients

Intravitreal methotrexate has been proven to be an effective treatment method for vitreoretinal lymphoma. However, keratopathy occurs as the major side effect during treatment in most cases. The purpose of this study is to describe the characteristics of primary central nervous system lymphoma (PCNSL) with intraocular involvement and to attempt to reduce the incidence of keratopathy caused by intravitreal methotrexate. The medical records of 22 PCNSL patients with intraocular involvement (33 eyes) were reviewed. Patients were divided into two groups. Group A (22 eyes) received the induction-consolidation-maintenance regimen, which consisted of intravitreal methotrexate injection at a dosage of 400 μg/0.1 ml twice a week for the first four weeks, weekly for the following eight weeks, and then monthly for the last nine months. Patients with a poor systemic condition were assigned to Group B (8 eyes), who were started on the treatment protocol described above and switched directly to monthly injection (9 months) when ocular remission was achieved. Blurred vision (31%) and floaters (25%) were common presenting symptoms. Vitritis was the most common clinical sign and was present in 29 eyes (90%) on B-ultrasound examination. Diagnosis was made by 25G-pars plana vitrectomy, and most diagnoses were diffuse large B-cell lymphoma. Ocular remission was achieved after 8.2 (SD = 4.6) injections of methotrexate. The mean VA (visual acuity) was improved from LogMAR 0.65 to 0.3 (P = 0.002). Keratopathy was observed in 21 eyes (66%) after an average of 8.2 (SD = 2.3) injections. With a reduced injection frequency, the incidence of keratopathy was lowered from 86.4% (Group A) to 25.0% (Group B) without ocular recurrence during follow-up. Intravitreal methotrexate is a safe, effective and flexible treatment for PCNSL patients with intraocular involvement. Keratopathy is the most common adverse effect and can be controlled by reducing the injection frequency.