|Year : 2014 | Volume
| Issue : 4 | Page : 145-146
Proper indications for vitrectomy–Myopic foveoschisis and proliferative diabetic retinopathy
Department of Ophthalmology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan 11217, R.O.C
|Date of Web Publication||1-Oct-2014|
Department of Ophthalmology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, Taiwan 11217
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chen SJ. Proper indications for vitrectomy–Myopic foveoschisis and proliferative diabetic retinopathy. Taiwan J Ophthalmol 2014;4:145-6
|How to cite this URL:|
Chen SJ. Proper indications for vitrectomy–Myopic foveoschisis and proliferative diabetic retinopathy. Taiwan J Ophthalmol [serial online] 2014 [cited 2020 Jul 12];4:145-6. Available from: http://www.e-tjo.org/text.asp?2014/4/4/145/204129
The recent advent of a wide-angle viewing system, small gauge vitrectomy, instrumentation, and machinery have opened up safer and more efficient ways of performing vitrectomy. The indication for vitrectomy also has expanded with the growing knowledge of vitreomacular interface diseases through studies of optical coherent tomography (OCT). For example, as Dr Yasushi Ikuno indicates in the review article in this issue of Taiwan Journal of Ophthalmology, entitled “Current concepts and cutting edge techniques in myopic macular surgeries”, myopic foveoschisis was not properly diagnosed before the era of OCT. This “tractional disease” is curable by dissecting the adherent vitreous cortex away from the retina with or without concomitant internal limiting membrane peeling through vitrectomy and intraocular forceps. The separation of these membranes from the macula allows the retina to bounce back slowly–sometimes within 6 months to 1 year–to the choroid with sealing of the intraretina and subretinal gaps. However, the indication for performing vitrectomy for myopic foveoschisis should be selected carefully, based on the findings of OCT.
In patients with foveoschisis with foveal detachment, the chances of visual improvement are 70–80%, compared with 40% in patients without foveal detachment. Once the foveoschisis progressed to a macular hole, the functional improvement further dropped to 30% after surgery. Therefore, patients with myopic foveoschisis should be monitored with OCT regularly and “go in” if foveal detachment develops. Waiting until the macular hole has developed would be too late.
However, what is the regular follow-up interval, how long should myopic foveoschisis be monitored for, and what are the risk factors for developing foveal detachment? A recent Japanese study showed that foveal detachment developed in 3.4% of patients (representing 7/207 eyes) with myopic foveaschisis during a follow-up period of at least 2 years. The extent of the schisis was the most significant factor for progression, which included increased retinal thickness, the development of an inner lamellar hole, and macular hole or foveal detachment. Avery extensive schisis with entire macula involvement, interestingly, is also more likely to develop spontaneous resolution of schisis. This is because there will be a greater likelihood of posterior vitreous detachment and internal limiting membrane (ILM) disruption, which releases the traction in patients with more extensive and severe schisis. Thus, questions of how long and how frequently should we follow patients with myopic foveoschisis to rescue myopic eyes from macular hole development remain unanswered because of the low incidence of foveal detachment and the surprisingly equal incidence (3.9%) of spontaneous resolution of schisis. One way is to remind our high myopic schisis patients is that once the visual acuity changes, they should be examined as soon as possible because it takes an average of 4.5 months to develop from the focal irregularity of outer retina thickening to an enlarged outer lamellar hole.
Vitrectomy was performed to prevent the development of a macular hole from myopic foveoschisis. However, a macular hole may unfortunately develop soon after an uneventful vitrectomy in 20% of patients who have the surgery. Dr Ikuno further reminds us that if the inner segment/outer segment line at the fovea was interrupted, chances for postoperative macular hole are high, regardless of the degree of myopia, age, staphyloma, or associated chorioretinal atrophy. However, it may be better to perform fovea-sparing ILM peeling in all cases of schisis. By preventing trauma of the Muller cell endfeet from the ILM at the fovea, the complication of macular hole decreased from 20% to 0%, based on two recent reports., However, all of these studies evaluating the proper indication, the timing, and the surgical technique for myopic foveoschisis were mainly retrospective in nature. Prospective local data are needed in Taiwan where high myopia is highly prevalent.
In contrast to the anatomical finding of OCT as an indication for surgery of myopic foveoschisis, visual acuity may be a contraindicator for surgery. For example, chances were low for vision improvement in eyes with complex proliferative diabetic retinopathy with visual acuity of no light perception. However, what about patients with poor visual acuity ranging from light perception to counting fingers? How much should their vision improve to justify the surgery? What are the associated factors that would indicate “no need for surgery”, even if the surgery is well performed?
In this issue, Dr Lin et al examined their patients with proliferative diabetic retinopathy with visual acuity equal to or less than counting fingers (CF) and found that patients with preoperative chronic macular detachment, broad fibrovascular proliferation, and poor renal function may in fact have deteriorated vision after an uneventful surgery. After excluding patients with significant postoperative vitreous hemorrhage, dense cataract and uncontrolled glaucoma, all of which would interfere with the interpretation of functional outcome, 10 (35.7%) of 28 patients did not have improved vision after at least 6 months of follow-up. In patients with baseline acuity less than or equal to counting fingers, the surgeon must pay attention to the risk factors that will be functionally “dull” for the difficult and time-consuming surgery. These factors may include chronic detachment (i.e., atrophic macula), vascular compromise (e.g., optic atrophy and sheathing vessels), renal insufficiency (e.g., high creatinine level), and severe fibrovascular proliferation (i.e., the four quadrants to the periphery).
In the future, we believe that proper indications for vitrectomy for different disease entities will evolve, depending on the findings of new diagnostic instruments such as OCT or depending on long-term studies of structural and functional change after surgery. Determining the proper indications for vitrectomy will be the first step for happy patients and surgeons.
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