An idiopathic macular hole is a condition where a full-thickness hole develops in the central retina or macula. The prevalence is approximately 0.3% or about 3 out of every 1000 people. Idiopathic macular holes are more common in women than in men, by a ratio of 3:1. We do not know what causes most macular holes (idiopathic), but other conditions which may be associated with macular holes include blunt trauma, macular edema, high myopia, and inflammatory conditions.
|Appearance of a macular hole as a photograph - left. OCT images of a normal macula [bottom right] and an full-thickness macular hole [top right].|
Pathogenesis and Clinical Findings
A recent development in diagnostic equipment called optical coherence tomography (OCT) indicates that separation of the vitreous gel from the retina with persistent adherence to the macula is the first event in the pathogenesis of an idiopathic macular hole. Macular holes are classified into stages 1 through stage 4. The earliest stage of macular hole is stage 1, and approximately 60% of stage 1 lesions resolve without treatment when the vitreous gel separates from the fovea. Visual acuity is typically minimally affected. Otherwise, the average time for progression of a stage 1 lesion to a full-thickness hole is approximately 4 months. Generally, visual acuity decreases with increasing hole size and stabilizes at 20/200 to 20/400 for stage 3 or 4 macular holes.
Since the status of the vitreous gel is so important in the pathogenesis of macular holes, this determines the risk of developing a hole in the fellow (other) eye. Fellow eyes with vitreomacular separation have less than a 5% chance of developing a macular hole; the risk of developing a macular hole in fellow eyes with no posterior vitreous detachment may be as high as 29%.
Surgery: Indications and Techniques
Vitrectomy with gas tamponade has been used for surgical treatment of macular holes since about 1991. Vitrectomy usually is not recommended for stage 1 macular holes, but is recommended for stage 2, stage 3, and stage 4 holes.
|Proposed mechanism of macular hole closure with an intraocular gas bubble. Face-down positioning causes the bubble to "push" against the hole and cause flattening.|
The technique involves removal of the vitreous gel, along with removal of any associated epiretinal membrane tissue. Recent reports indicate that removal of the internal limiting membrane (ILM), may increase success rates even further. Once the gel and membrane(s) are removed, an air bubble is placed into the vitreous cavity. Then one of two options are chosen.
- A nonexpansile concentration of long-acting gas (SF6 or C3F8) is exchanged with the air. For most patients, strict face-down positioning is recommended for 14 days. Some retina surgeons are doing this for less than 14 days (4-7 days), although the success rates for this have yet to be firmly established. Travel by air or to high altitudes is prohibited while the gas bubble is present, as it would expand in the lower atmospheric pressure and severely increase the intraocular pressure. In addition, dental work or general anesthetic with nitrous oxide (laughing gas) is contraindicated because it diffuses into the gas bubble also causing it to expand. Vision is very blurred while the gas bubble is present. Depending on the type, the bubble may remain in the eye for about 2 weeks (SF6) to 2 months (C3F8).
- If it is impossible for the patient to maintain the face-down position, a clear silicone oil can be used instead of gas. Face down positioning is overnight, and the patient can be in any position other than flat on his/her back while the silicone oil is present. However, this approach necessitates an additional surgical procedure for oil removal approximately 3 months later, and has a lower success rate than intraocular gas (see below). Because of the different refractive properties of silicone oil, vision is also very blurry while the oil is present.
Complications of surgery include progression of nuclear sclerotic cataract (more than 75% of patients within 3 years after surgery), retinal tears (2-19% of patients), retinal detachment (3%), visual field defects, phototoxic injuries, and endophthalmitis (less than 1%).
Current techniques strive to minimize the risk of retinal tear or detachment by examining the peripheral retina before closing, and prophylactic laser in selected cases. Visual field defects occasionally occur peripherally and are thought to be the result of dehydration and/or high air infusion pressure during surgery. This is minimized by using low to normal infusion pressures and not allowing air to flow freely through the eye during the air-fluid exchange. Phototoxic injuries can occur from the fiber optic light source. These injuries are minimized by using 50% of normal light intensity during the vitrectomy, and keeping the time working around the hole to 10 minutes or less.
Anatomic and Functional Outcome
The current anatomic success rate of vitreous surgery for idiopathic macular holes is approximately 80% to 100% in nonrandomized studies. A recent study comparing silicone oil and gas showed that there was a significantly higher success rate for gas (91%) compared to silicone oil (65%). Eighty-five percent of eyes show an improvement of at least two lines of vision on the Snellen eye chart. The likelihood of recovering visual acuity of 20/40 or better ranges from approximately 25% to 40%, and is thought to be related to the stage and duration of the macular hole. It is generally felt that surgery within the first sixth months results in better vision than in patients with macular holes of longer duration.
Reopening of a successfully closed macular hole is relatively uncommon, ranging from 2-10%. With reoperation, the rates of anatomic and functional success are high, and comparable to those of patients undergoing the first operation.
Nonidiopathic Macular Holes
The surgical approach is the same for nonidiopathic macular holes as for idiopathic macular holes. The anatomic success rates are similar to those observed for idiopathic macular hole. The visual results vary, depending on the underlying cause and duration of the macular hole.
Hints from Former Patients
We collect several hints hat can make the week of postoperative positioning easier. Most of these hints are practical things that may not be considered before the surgery.
- You will need determination to keep your head down 24 hours a day.
- It helps to practice taking a bath or shower, brushing your teeth, walking, eating and laying face down before surgery.
- It also helps to practice looking downward while having someone get drops into your eye. Practice with artificial tears.
- You will need straws to drink all fluids.
- You may need a lap tray to eat from as tables may be too high for eating with your head down.
- You may want a comfortable neck collar to rest your head on.