THE INTEGRAL ROLE OF OCT IN MANAGEMENT OF MACULAR HOLE

Optical coherence tomography (OCT) has improved retina specialists’ ability to manage full-thickness macular hole (FTMH) in multiple ways. OCT enables definitive diagnosis, aids surgical planning, and provides information that may prognosticate postoperative outcomes.

PREOPERATIVE OCT

OCT has surpassed clinical examination as the most sensitive way to diagnose FTMH. Based on slit lamp examination and indirect ophthalmoscopy alone, FTMH can appear similar to lamellar hole, pseudohole, or vitreomacular traction (VMT). It’s crucial to utilize OCT to differentiate between these distinct entities because they are managed with vastly different approaches. As I instruct trainees who work with me in our program, it is also very important—regardless of which OCT machine is used—to review all captured images. When only single-line raster scans are reviewed, small macular holes can be overlooked.

Once FTMH is diagnosed, OCT enables precise measurement of the hole’s size. Size affects treatment decision-making and is one factor that informs visual and anatomic prognosis. [International Vitreomacular Traction Study Group size classification: small (<250 µm), medium (250-400 µm), large (>400 µm).]¹

SURGICAL PLANNING AND EXECUTION

OCT should also be used prior to FTMH surgery to confirm the presence or absence of persistent VMT, a key consideration in surgical planning. Even when there appears to be a complete posterior vitreous detachment on clinical examination, I find that patients with cortical vitreoschisis may still have partial attachment of the hyaloid face to the underlying retinal surface. This presents the risk of the surgeon inadvertently peeling tissue other than the internal limiting membrane (ILM) during FTMH surgery, which detracts from the likelihood of success. (I peel the ILM in every FTMH surgery regardless of the hole’s size, but there is some data to suggest that outcomes may not differ with or without ILM peeling for smaller FTMH.²)

Three-dimensional volume scans are particularly helpful for determining the extent and location of vitreous adhesions to the retina. When OCT reveals VMT, the surgeon knows to elevate the hyaloid before initiating ILM peeling.

OCT can also alert the surgeon to the presence of epiretinal membrane, which can occur concurrently with FTMH and must be removed prior to ILM peeling. OCT may also be helpful in guiding the surgeon to the most efficacious place to begin the peeling process. Intraoperative OCT is a relatively new technology that can be used to guide surgeons through these aspects of the procedure in real-time.

My preferred treatment for FTMH is pars plana vitrectomy with ILM peeling and gas tamponade; however, other options, such as ocriplasmin or pneumatic vitreolysis with air or gas, can be considered. Especially for small holes with persistent VMT, these other options may be effective and spare the patient a surgical procedure.

PROGNOSTIC CLUES

While the postoperative closure rate of FTMH in general has been reported to be greater than 90%, visual acuity (VA) outcomes following closure can be more variable. OCT-measured FTMH size is one factor that may affect postoperative visual acuity. Smaller holes tend to have a higher probability of closure postoperatively, and they also seem to have better VA outcomes.³

Aside from FTMH size, another preoperative OCT finding that may be associated with the likelihood of a FTMH to close is a slight lifting of the hole edges with the presence of cystoid macular edema (Figure 1).

Figure 1. Based on minimum linear dimension, the OCT caliber function (yellow bracket) indicates a medium-size full-thickness macular hole. Overlying posterior vitreous detachment with operculum is also seen. Cystoid macular edema and slight lifting can be observed at the hole edges. These features are thought to predict a greater likelihood of closure following surgical repair.
Image courtesy of Christina Y. Weng, MD, MBA — Figure 1. Based on minimum linear dimension, the OCT caliber function (yellow bracket) indicates a medium-size full-thickness macular hole. Overlying posterior vitreous detachment with operculum is also seen. Cystoid macular edema and slight lifting can be observed at the hole edges. These features are thought to predict a greater likelihood of closure following surgical repair. Image courtesy of Christina Y. Weng, MD, MBA

For reasons not completely understood, patients with these findings tend to have better closure rates. One theory is that these findings indicate a hole of shorter duration.

POSTOPERATIVE OCT

Postoperative OCT findings can also help to explain patients’ VA. Loss of integrity of the ellipsoid zone and outer retina layers can be a limiting factor,⁴^,⁵ and a decrease in inner macular volume has been shown to correlate with a decrease in VA.⁶ On the other hand, after hole closure, it is not uncommon for OCT to show a small pocket of subretinal fluid or subfoveal lucency (Figure 2). This generally resolves with time and does not seem to correlate with worse visual outcomes.

Figure 2. One month after pars plana vitrectomy, internal limiting membrane peel, air-fluid exchange, and gas tamponade for repair of full-thickness macular hole, OCT confirms anatomic closure of the hole along with a subfoveal lucency that is often seen during the early postoperative period and typically not a concern.
Image courtesy of Nitish Mehta, MD — Figure 2. One month after pars plana vitrectomy, internal limiting membrane peel, air-fluid exchange, and gas tamponade for repair of full-thickness macular hole, OCT confirms anatomic closure of the hole along with a subfoveal lucency that is often seen during the early postoperative period and typically not a concern. Image courtesy of Nitish Mehta, MD

Interpretable OCT images can be obtained as early as postoperative day 1, even if gas tamponade is present. While I tend to wait until week 1 or month 1 to order a repeat OCT, day-1 scans can be useful. For example, FTMH may close as soon as the next day after surgery, and some surgeons use postoperative day-1 OCT findings to guide how long to position the patient face-down.⁷^,⁸ Surgeons who use ILM or retinal free flaps in repairing FTMH may also find postoperative day-1 OCT beneficial in ensuring proper localization of the adjuvant tissue.

Finally, it is worthwhile to mention that I personally find both preoperative and postoperative OCT images to be invaluable for patient education and motivation. Showing patients their OCT images truly helps them to understand their condition, the need for treatment, and the potential outcomes more fully.

REFERENCES

Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology. 2013;120(12):2611-2619.
Tadayoni R, Gaudric A, Haouchine B, Massin P. Relationship between macular hole size and the potential benefit of internal limiting membrane peeling. Br J Ophthalmol. 2006;90(10):1239-1241.
Ip MS, Baker BJ, Duker JS, et al. Anatomical outcomes of surgery for idiopathic macular hole as determined by optical coherence tomography. Arch Ophthalmol. 2002;120(1):29-35.
Chang YC, Lin WN, Chen KJ, et al. Correlation between the dynamic postoperative visual outcome and the restoration of foveal microstructures after macular hole surgery. Am J Ophthalmol. 2015;160(1):100–106.e1.
Ruiz-Moreno JM, Arias L, Araiz J, García-Arumí J, Montero JA, Piñero DP. Spectral-domain optical coherence tomography study of macular structure as prognostic and determining factor for macular hole surgery outcome. Retina. 2013;33(6):1117-1122.
Pilli S, Zawadzki RJ, Werner JS, Park SS. Visual outcome correlates with inner macular volume in eyes with surgically closed macular hole. Retina. 2012;32(10):2085-2095.
Masuyama K, Yamakiri K, Arimura N, Sonoda Y, Doi N, Sakamoto T. Posturing time after macular hole surgery modified by optical coherence tomography images: a pilot study. Am J Ophthalmol. 2009;147(3):481-488.e2.
Sano M, Inoue M, Itoh Y, et al. Duration of prone positioning after macular hole surgery determined by swept-source optical coherence tomography. Retina. 2017;37(8):1483-1491.

Dr. Weng is an associate professor of ophthalmology and director of the vitreoretinal disease and surgery fellowship program at the Baylor College of Medicine in Houston.

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