To investigate whether the photoreceptor layer status of the detached retina, which has the potential to plug the macular hole (MH), can predict postoperative visual acuity (VA).
Retrospective, consecutive, observational case series.
A consecutive series of 48 eyes in 48 patients with surgically closed MHs were recruited into the study. Spectral-domain optical coherence tomography (SD OCT) images were obtained preoperatively and postoperatively. Length gaps between photoreceptor layers and the preoperative diameter of the basal MH in the detached part of the retina was calculated for the photoreceptor outer segment (OS) and the external limiting membrane (ELM). The postoperative photoreceptor layer status at the fovea, including continuity of the ELM line, inner segment ellipsoid line (ISe), and cone outer segment tip (COST) line, was categorized by graders.
The preoperative OS gap length and ELM gap length correlated significantly with postoperative VA. A larger OS or ELM gap length was associated with a more severe postoperative photoreceptor layer status. Eyes with a moderately reflective lesion had a significantly longer OS gap length and ELM gap length, significantly worse postoperative VA, and more severe photoreceptor layer status than did eyes without such a moderately reflective lesion. Eyes with a better postoperative COST status had significantly better postoperative VA ( P = .0465).
OS and ELM gap length, which represent the degree of insufficiency of MH plugging, was strongly correlated with postoperative VA; moreover, these preoperative parameters were associated with the postoperative photoreceptor layer status, including glial cell proliferation.
Idiopathic macular hole (MH) is a condition found in the eyes of middle-aged and older individuals and causes decreased visual acuity as well as metamorphopsia. Since first reported by Kelly and Wendel in 1991, MH surgery has continued to improve. Today, the MH surgical procedure has been virtually perfected, with pars plana vitrectomy (PPV), internal limiting membrane peeling, and the use of a gas tamponade allowing a high rate of MH closure to be achieved. However, despite anatomic closure of the MH, some patients have persistent symptoms, and identification of a predictor of postoperative visual outcomes continues to be an urgent quest in MH surgery.
Imaging technology in optical coherence tomography (OCT), which provides cross-sectional images of the retina, has enabled clinicians not only to confirm successful MH closure, but also to investigate candidate predictors of postoperative visual outcomes. Several investigators have found that the degree of disrupted photoreceptor layers, including the inner segment ellipsoid line (ISe), the external limiting membrane (ELM), and the cone outer segment tip (COST), in postoperative OCT images of closed MHs correlated well with postoperative visual outcome. Thus, severe cone photoreceptor damage and the dynamic healing process can be monitored by OCT.
One of the main concerns of clinicians is identifying a prognostic factor in MH surgery. To predict postoperative visual outcome, investigators have evaluated several preoperative OCT features, including ISe or COST defect length across the MH. However, although these parameters may reflect the damage to the photoreceptors in the parafoveal or juxtafoveal area, they may not necessarily correspond to the photoreceptor damage at the center of the fovea, without a direct evaluation of the photoreceptor layer of the detached retina that has the potential to plug the hole.
In this study, we hypothesized that whether the detached part of the retina retained a sufficient amount of photoreceptors to plug the MH may determine the postoperative photoreceptor layer status, and in turn visual acuity (VA), after MH closure. We propose a new index for the preoperative MH, using spectral-domain (SD) OCT, which represents the insufficiency of the photoreceptor layers relative to the MH size, and explored its clinical relevance.
This was a retrospective, consecutive, observational case series study, which adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board at Kyoto University Graduate School of Medicine for retrospective review of existing patients’ data. We retrospectively reviewed 102 eyes in 101 patients who underwent MH surgery. All patients visited the Kyoto University Hospital, Kyoto, Japan, between December 1, 2007 and November 30, 2011. The inclusion criteria were the availability of SD OCT images of sufficient quality and the presence of a Gass stage 2, 3, or 4 idiopathic full-thickness MH as determined by OCT imaging. All patients had undergone comprehensive ophthalmologic examinations, including measurements of best-corrected visual acuity (BCVA), slit-lamp biomicroscopy, color fundus photography, and SD OCT before surgery and 12 months postoperatively. Exclusion criteria were previous and/or coexisting conditions, such as mature cataract, high myopia (more than 26.5 mm), traumatic MH, recurrent MH, other retinal disease, and past intraocular surgery.
Optical Coherence Tomography
Retinal sectional images before and after surgery were obtained using SD OCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany) and horizontal scans through the center of the MH were analyzed. The scans on which the diameter was the largest were chosen for each subject from the records of raster scans or multiple single horizontal line scans over the MH for the subsequent analyses.
Evaluation of photoreceptor layer features in the preoperative images
In order to calculate the length of the gap between photoreceptor layers in the lateral direction and the basal diameter of the MH in the detached part of the retina, the ELM line and the outermost layer of the detached retina, which was considered to correspond to the photoreceptor outer segment (OS), were analyzed. ISe was not used, as the line was unclear in the detached part of the retina. The OS length of the detached retina was defined as the length of the outermost edge of the detached part of the sensory retina ( Figure 1 ). The length of the ELM line at the detached part of the retina was defined as the length from the intersection of the line perpendicular to the retinal pigment epithelium (RPE) line at the beginning of the retinal detachment with the ELM line to the stump of the ELM line. The basal diameter of the MH was defined as the linear length between the nasal and temporal side of the retinal detachment. In this study, the length of the gap of the OS line and the ELM line were calculated as follows:
OS length gap = diameter of basal hole − ( OSn length + OSt length )
ELM length gap = diameter of basal hole − ( ELMn length + ELMt length )