A 58-year-old female, with a history of hypertension and type 2 diabetes for 10 years, presented as a new patient to our clinic for an annual dilated retail exam due to her diabetes. Last HgBA1c was 6.6, and current medications included metformin and lisinopril. She reported no complaints other than feeling she may need an update on her glasses. BVCA was 20/20 OU with a mild hyperopic astigmatic prescription. All entrance tests, including finger counting fields, were unremarkable.
Dilated retinal exam revealed an elevated lesion inferotemporal OS with distinct margins and visible vasculature (Fig 1, 2). Acquired retinoschisis was suspected, and the patient was sent to retina clinic for a second opinion. The diagnosis of retinoschisis was confirmed at that visit, and an OCT of the area was performed, which revealed splitting of the retinal layers, with the outer layer still attached to the RPE (Fig 3). A Humphrey 30-2 Visual Field was also performed which revealed a full field with no defects. The patient has been followed on a yearly basis since, with no progression on repeat exams.
This patient has an acquired retinoschisis, one of the two major types of retinoschisis. Retinoschisis is defined as splitting of the neurosensory retina, typically within the outer plexiform layer. There is some variability in their presentation of acquired retinoschisis, with some lesions appearing much more bullous, while other lesion scans are somewhat flatter and more shallow. Other types of retinoschisis include X-linked juvenile retinoschisis (XLRS) which presents in younger, symptomatic, almost exclusively male patients and myopic macular retinoschisis which is a complication of high myopia.
Acquired retinoschisis (RS) tends to happen later in life, although there have been reports of cases in young adults as well as children. The overall incidence of acquired RS is approximately 1% but increases to 3.9% in patients from 60-80 years of age. It most commonly affects the inferotemporal retina, with supertemporal retina being the second most common location. They are bilateral upwards of one-third of the time. They are typically benign, and often found on routine exams. However, due to the splitting of the retinal layers, they do cause an absolute visual field defect, so some patients with large RS may be symptomatic.
There can also be inner or outer wall breaks within the RS. Outer wall breaks happen approximately 11-24% of the time, are often larger than inner holes and have surrounding pigment. Inner holes are smaller, less common, and appear like an atrophic hole. Either hole has been associated with an increased risk of detachment, so a retinal consult is advised. Both inner and outer holes together are considered quite dangerous and would warrant a more timely referral due to their higher rate of detachment. Lastly, acquired RS do not seem to be negatively affected either by cataract surgery or the development of a posterior vitreous detachment. If there are no holes, acquired RS are generally considered benign and can be monitored yearly, unless enlargement or symptoms.
One of the biggest diagnostic challenges with acquired RS is being able to differentiate it from a retinal detachment, which can be a true ocular emergency. In general, acquired RS tend to be more translucent, with underlying visible vasculature, versus the more opaque appearance of a retinal detachment. Further, the borders of RS tend to be well demarcated, with a less flexible, overall smoother appearance than a detachment, which often undulates, especially with movement. Lastly, as mentioned earlier, an RS should be associated with an absolute VF defect versus a relative defect with detachment. However, this may not be helpful, depending upon the location and extent of the RS. OCT has really provided the best way to distinguish between a RS and a retinal detachment. An RD will appear as the entire retina separated from the underlying RPE on OCT, while a RS will show the RPE still attached to neurosensory retina, with a splitting of the retinal layers.
Should progression be noted, a prompt referral to a retinal special is recommended. Progression has been noted to happen more in myopic patients versus hyperopic patients. It is rather rare to have a detachment into the macula (about 2% of cases) but those that do detach require retinal surgery. Unfortunately, the literature shows poor success rate with surgery, with many patients needing multiple surgeries. As an aside, prophylactic laser to treat the leading edge of the schisis to prevent progression has not seemed helpful
Though not extremely prevalent, acquired retinoschisis can be encountered in practice. The most difficult diagnostic dilemma is often making the correct diagnosis, and it must be differentiated from the far more serious retinal detachment. OCT has proven to be the most definitive way to do so if imaging is possible due to the peripheral location of the lesion. The majority of acquired retinoschisis are non-progressive and can be monitored on a yearly basis with repeat DFE and appropriate patient education.