To determine the retinal features seen on enhanced spectral-domain optical coherence tomography (SD-OCT) associated with foveal retinal detachment in eyes with myopic macular retinoschisis.
Retrospective case series.
We reviewed fundus photographs and conventional and enhanced SD-OCT images of 21 eyes of 19 patients with myopic macular retinoschisis. Features seen on enhanced SD-OCT images were identified and compared between eyes with and without foveal detachment.
On enhanced SD-OCT images, the retinoschisis in the outer retina was accompanied by splitting in the inner plexiform layer (IPL) in 11 eyes (50.0%) and a detachment of the inner limiting membrane (ILM) in 11 eyes (50.0%) in the superior and/or inferior peripheral macula; 9 eyes (42.9%) had both features. Multiple columnar structures were seen throughout the outer retinoschisis in 20 of 21 eyes (95.2%), and in ILM detachment/IPL retinoschisis in all eyes. Thirteen eyes had or progressed to a foveal detachment; an ILM detachment developed in 10 eyes (76.9%) with a foveal detachment and in 1 eye (12.5%) without a foveal detachment ( P = .008). IPL retinoschisis was detected in 8 eyes (61.5%) with a foveal detachment and 3 eyes (37.5%) without a foveal detachment, but this difference was not significant.
An ILM detachment in the superior and/or inferior peripheral macula was associated with a foveal retinal detachment in highly myopic eyes with macular retinoschisis. This feature may indicate strong tractional forces on the ILM that are transmitted to the outer retina through the dense columnar structures, resulting in a foveal retinal detachment.
Optical coherence tomography (OCT) has shown that myopic macular retinoschisis (also called foveoschisis) is not uncommon in highly myopic eyes. Retinoschisis was detected in 9% to 34% of highly myopic eyes with a posterior staphyloma. Based on the OCT features of untreated and treated eyes, the pathogenesis of myopic macular retinoschisis has been attributed to strong traction on the retina exerted by residual posterior vitreous cortex, an internal limiting membrane (ILM), retinal vessels, or a combination of these. Axial length elongation and/or formation of posterior staphyloma in highly myopic eyes may generate the inward tractional force exerted by these factors. This is strongly supported by the remission of the retinoschisis after vitrectomy combined with ILM peeling, which theoretically releases the tractional forces exerted by the posterior vitreous cortex and the ILM and partly by the retinal vessels in the area from which the ILM was peeled.
Myopic macular retinoschisis progresses to a retinal detachment in 21% to 43% of eyes, whereas this disease is often stable for many years without progression to a retinal detachment in other eyes. Development of a foveal retinal detachment in myopic macular retinoschisis impairs vision more severely. Thus, it is clinically important to identify the risk of progression of macular retinoschisis to a foveal retinal detachment. However, it is difficult to determine which eyes with myopic macular retinoschisis develop a retinal detachment. With more recently developed spectral-domain (SD) OCT technology, macular features can be visualized in great detail. Commercially available SD-OCT instruments acquire images 43 to 133 times faster than time-domain (Stratus) OCT instruments. High-speed imaging allows acquisition of high-definition SD-OCT B-scan images or averaging of multiple OCT B-scans at each location of interest on the retina to reduce speckle noise, thus providing a more detailed view of the macular anatomy. In the current study, we evaluated SD-OCT images enhanced by high definition or reduction of speckle noise obtained from eyes with myopic foveoschisis to differentiate the morphologic characteristics between eyes with and without a retinal detachment.
Twenty-one highly myopic eyes of 19 patients (3 men, 16 women) with macular retinoschisis who underwent enhanced SD-OCT examinations were included. In this study, eyes with an axial length equal to or greater than 26.00 mm were defined as highly myopic.
All patients underwent comprehensive ophthalmologic examinations, including autorefractometry, uncorrected and best-corrected visual acuity measurements using the 5-meter Landolt chart, axial length measurement using the IOL Master (Carl Zeiss Meditec, Dublin, California, USA), slit-lamp examinations, intraocular pressure measurements using Goldmann applanation tonometry, dilated indirect slit-lamp biomicroscopy, and color fundus photography.
Enhanced SD-OCT Examination
Experienced ophthalmologists examined all eyes using primarily SD-OCT instruments. Enhanced SD-OCT imaging was performed with the Spectralis HRA+OCT system (Heidelberg Engineering, Heidelberg, Germany), RTVue-100 (Optovue, Fremont, California, USA), and/or Cirrus HD-OCT (Carl Zeiss Meditec) to investigate the retinal microstructures. Enhancement of the B-scan images was achieved by reducing the speckle noise in Spectralis HRA+OCT and RTVue-100 by averaging 12 to 50 multiple OCT B-scans at each precise location of interest on the retina. Enhancement of the B-scans in Cirrus HD-OCT was achieved by acquisition of high-definition 6-mm B-scans (4096 axial scans/image) in 0.3 second per image.
The demographic data from all the patients (16 women, 3 men) are shown in Table 1 . The ages of the patients ranged from 37 to 77 years (mean ± SD, 65.9 ± 6.6 years). The axial lengths ranged from 26.8 to 34.2 mm (mean ± SD, 29.7 ± 2.0 mm). Of the 21 eyes, 20 (95.2%) had posterior staphyloma.
|Case||Age (Years)/ Gender||R/L||Axial Length (mm)||Posterior Staphyloma||Foveal RD||Columnar Structure||ILM Detachment||Schisis in IPL||PHM|
On OCT images, myopic macular retinoschisis in the outer retina was seen in all eyes. On enhanced SD-OCT images, splitting of the outer retina appeared to be present between the outer plexiform layer and the outer nuclear layer, because in all eyes the highly reflective layer representing the inner plexiform layer and 2 highly reflective lines representing the external limiting membrane (ELM) and the photoreceptor inner and outer segment junction (IS/OS) were seen in the anterior and posterior borders of the retinoschisis, respectively ( Figures 1, 2, 3 , and 4 ). In 20 of 21 eyes (95.2%), multiple columnar structures were seen widely within the retinoschisis as long, straight, highly reflective lines at the fovea and throughout the retinoschisis. In 6 eyes (28.6%) in which progression to a foveal retinal detachment was observed during follow-up, the columnar structures within the area of the retinal detachment shortened markedly and lost the columnar shape as if they shrank ( Figure 3 ). In addition to the retinoschisis in the outer retina, there were 2 other intraretinal separations on the SD-OCT images. Retinoschisis was found at the level of the inner plexiform layer (IPL; termed IPL schisis in this study) in 11 eyes (50.0%), an inner limiting membrane (ILM) detachment was seen in 11 eyes (52.4%), and both the features were found in 9 eyes (42.9%). In the space beneath the ILM and within the IPL retinoschisis, multiple columnar structures were observed similar to those seen in the retinoschisis in the outer retina ( Figures 1 and 2 ). The ILM detachment was in the superior and/or inferior peripheral macula on vertical B-scans in all 11 eyes, but it was seen in only 2 eyes on the horizontal B-scans. A comparison with simultaneously obtained infrared images indicated that the retinal vessels were present in the area of the ILM detachments in all eyes ( Figures 1 and 2 ). Microfolds were seen in 2 of the 21 eyes (9.5%), which corresponded to a retinal vessel; 1 was seen within an area with an ILM detachment and IPL retinoschisis ( Figure 2 ) and the other was not associated with these features ( Figure 3 ). A posterior hyaloid membrane was seen in only 3 eyes (14.3%) ( Figure 4 ).