PVRL is a disease associated with a coexistent CNS lymphoma in 80% of cases with poor prognosis. Developing objective, unified and repeatable indicators to evaluate the efficacy of treatment for PVRL is important. Traditionally, changes in the amount of vitreous cells or BCVA are common criteria used to determine the response to treatment. However, from month to month, slight changes in the amount of vitreous cells are difficult to ascertain. BCVA does not always vary with changes in PVRL. The need for further information on indicators that can monitor the efficacy of treatment in patients with PVRL is paramount.
In this report, we present the characteristic OCT features of PVRL at the initial visit, derived from a series of SD-OCT images of consecutive eyes with biopsy-proven PVRL. These features were in accordance with previously published reports[2,11,12]. We further present that these observed features decreased gradually and finally vanished after therapy. Compared with former previous reports[11,12,15], our study obtained a longitudinal OCT images in the same PVRL patient and in a relatively large sample before and after the treatment. This study therefore provides considerable support for the use of SD-OCT as an aid to monitor the responsiveness of PVRL to treatment. We also present that in some eyes, BCVA remained unchanged after treatment, while SD-OCT showed improvement. Therefore, we believe that OCT is superior to BCVA in monitoring PVRL treated with intravitreal injections of MTX.
We confirm that OCT features in patients with PVRL can improve with therapy and finally vanish. In our cases, after the induction phase, all subretinal fluid in cases (case 4 and case 5) with RD was absorbed, and other features were significantly reduced. After the consolidation phase, in case 4, OCT abnormalities, except for hyperreflective foci in the posterior vitreous, disappeared, and OCT abnormalities in other cases further improved. After the maintenance phase, all of the PVRL OCT features vanished. OCT features were speculated to represent infiltrating lymphoma cells at various levels in the retina[11,12], and indeed, we present further evidence of this phenomenon since these OCT features finally disappeared after the commencement of effective lymphoma-specific therapy.
We believe that the same VRL-OCT features may have different prognoses. In the reported series, some manifestations at, below or above the level of RPE were resolved, with the OCT images returning to normal, while other manifestations were resolved, with the disruption of the interdigitation zone and the ellipsoid zone. We speculate that the reason for these remaining disruptions was that lymphomatous infiltration contributed to RPE dysfunction, leading to photoreceptor outer segment abnormalities. This finding has also been reported by Keino. In their cases, the most common OCT finding was abnormality of the ellipsoid zone, both at the initial visit and during the follow-up period. In agreement with us, these authors considered the reason for these findings could possibile be that lymphomatous infiltration into the RPE leads to photoreceptor outer segment abnormalities.
Additionally, homogenous hyperreflectivity in the full-thickness retina on OCT can have different outcomes. Homogeneous lesions are considered to be infiltrating tumor cells that replace the entire layer of the retina. After effective treatment, as shown in the representative case, these hyperreflective lesions gradually diminished, and retina stratification reappeared. Finally, the retina returned to normal or the inner layer atrophied and thinned, and the structure of the outer layers was destroyed.
Subretinal fluid can be absorbed rapidly after treatment, and fibrous material deposits can be detected in the outer retina, accompanied by the destruction of the normal structure of the retina. It is noteworthy that in eyes with exudative retinal detachment at the initial visit, the final BCVA was poor. We believe that the destruction of the retina can be the reason for the poor visual acuity. We recommend exudative retinal detachment as an indicator of poor visual prognosis.
We believe that OCT is superior to BCVA in monitoring PVRL treated treatment with intravitreal injections of MTX. As shown in our cases, BCVA remained unchanged after treatment in 4 eyes (left eyes of cases 3, 5, 9 and 10), although SD-OCT and fundus photography showed marked improvement. In the left eyes of cases 3, 9 and 10, macular fovea was not involved, and the cause of poor BCVA was not PVRL but complicated cataract. Therefore, OCT and fundus photography showed improvement in the tumors outside the fovea, while their BCVA remained unchanged. In the left eye of case 5, although OCT showed that subretinal fluid was absorbed rapidly after treatment, BCVA remained unchanged.
Unfortunately, in the medical record of these cases, the amount of vitreal cells was only recorded as present or absent. We are unable to make an accurate comparison between the effectiveness of therapy based on SD-OCT and that based on vitreous cells under an ophthalmoscope.
Additionally, our study has several other limitations due to its retrospective nature. Our SD-OCT images were limited to the macula, so changes in the peripheral retina and optic disk could not be obtained. The patients should be followed up for a longer time to further confirm whether the patients that were thought to have been cured based on the SD-OCT images were truly cured.