Laser Treatment of Retinal Breaks

A look at the clinical indications and technique.

STEVE CHARLES, MD

Though roughly 70% of the population develop a posterior vitreous detachment, only about 4% of the population have retinal breaks.¹ Of these patients, only about 6 in 10000 develop retinal detachments. Patients go on to develop retinal detachment after retinopexy in about 2% of cases, with the complication rate of retinopexy remaining exceedingly low and difficult to measure.² Determining the need for treatment is multifactorial and complex at best.

The most conservative position is that only symptomatic flap tears should be treated.³ However, many large horseshoe tears, which all surgeons would agree need treatment, are asymptomatic as many surgeons have discovered in examinations carried out before laser-assisted in situ keratomileusis (LASIK), and even routine examinations. I suspect most physicians that espouse the conservative position are significantly more aggressive in their clinical practice.⁴

Clinical characteristics in favor of treatment include larger breaks, flap tears instead of round holes, breaks outside lattice, superior location, and evidence of vitreous traction.^3,5 Larger breaks allow greater transhole flow, potentially exceeding the capacity of the retinal pigment endothelium (RPE) pump to stabilize a subclinical retinal detachment. Round tears are thought to be less likely to have traction, but they are often noted to have traction at the time of vitrectomy. Operculated breaks are least likely to have vitreous traction.⁶ Rolled edges are said to be indicative of tangential traction, but the internal limiting membrane (ILM) is elastic, and surgically resected normal retina immediately rolls inward. Superior breaks are probably slightly more significant because gravity will decrease the likelihood of a stable subclinical retinal detachment.

Pigmentation indicates chronicity, not adherence; therefore, pigmentation is only a relative contraindication.⁷ Other factors favoring treatment include a history of retinal detachment in the other eye, a family history of retinal detachment, and physically active careers and/or sports.⁸ Surgeons cannot predict which patients will be struck by an air bag, experience a serious fall, or suffer another type of trauma suggesting that trying to guess who needs laser by evaluating life style is problematic.

Socioeconomic situations suggesting that the patient is less likely to return for follow-up should also be taken into account. Most surgeons believe that anticipated LASIK, cataract removal, or vitrectomy surgery is a reason to be aggressive about treating asymptomatic retinal holes and similar low-risk breaks. A high percentage of the population will ultimately have cataract surgery, suggesting the need to treat lower-risk breaks in most patients.⁸

COMPARISON WITH CRYOPEXY

Unlike laser, cryopexy disperses living RPE cells, possibly increasing the risk of proliferative vitreoretinopathy (PVR) and epimacular membranes.⁹ The PVR and epimacular membranes that are said to be complications of treating retinal breaks could actually be also directly related to the retinal break causing the retinal glial cells and RPE cells to have loss of contact inhibition.¹⁰ Cryopexy produces inflammation and exudation but no immediate adherence, while laser produces moderate, immediate adherence and no exudation. In addition, cryopexy is more painful and produces conjunctival damage as well.^11,12

TECHNIQUE

Spot spacing is a judgment issue in determining the optimal number of rows. Wide spacing ("underlap") raises the issue of subretinal fluid leakage between the spots, while overlapping results in areas of overtreatment. Most surgeons use approximately 3 rows of confluent spots. Many surgeons do not treat round holes within lattice degeneration unless breaks outside lattice are present that require laser. While use of discrete circular spots is the standard of care, movement of the laser using a painting technique increases uniformity of the thermal effect, although painting potentially produces more pain due to heat diffusion.

Selecting optimal power is also a judgment issue. Undertreatment may not produce enough pigmentation to subsequently validate treatment adequacy, while so-called heavy treatment may produce excessive inflammation, possibly leading to PVR and epimacular membranes. It is crucial to completely surround the retinal break. Many patients receive insufficient treatment anterior to the break. Three-mirror contact lenses (150° field of view) are the most widely used contact lenses used to treat retinal breaks, but various wide-angle (>130°) lenses can be used for all but the most peripheral breaks if care is taken to ensure treatment anterior to the break. The Eisner (Crystal Lake, IL) scleral depressor fits over the 3-mirror lens and works well, although it is somewhat more uncomfortable and generally underutilized. Ensuring maximal dilation of the pupil is important to enable adequate treatment anterior to the break. If posterior capsular opacification or cortical cataract makes visualization anterior to the break impossible even with scleral depression, the anterior treatment can be continued to the ora at both ends of the break or laser retinopexy can be combined with cryopexy.

The Pascal laser (Optimedica, Santa Clara, CA) produces a precision pattern of shorter-duration spots. The pattern results in greater spacing uniformity. Using 30-millisecond–duration burns results in significantly less pain from thermal diffusion to the choroid while not increasing treatment time. The arc pattern works well for retinal breaks.

The laser indirect ophthalmoscope (LIO) is useful for wheelchair patients and patients with spinal deformities, such as severe osteoporosis or scoliosis. The LIO is also ideal for treating through gas bubbles using trial and error head/bubble positioning to optimize focus and access to the breaks. The LIO is ideal for operating room use on children or for treatment of the contralateral eye during retinal detachment surgery often under general anesthesia. LIO treatment is easily utilized with scleral depression.

Retrobulbar blocks are seldom needed with laser retinopexy. There is increased risk of globe penetration in myopic patients with thin sclera, who, of course, are the very patients with a higher incidence of retinal breaks.

Patients can return to full activity 14 days after laser treatment because tensile strength reaches the maximum level at this time. Often patients are counseled unnecessarily to avoid work, housekeeping, and exercise for extended periods.

The longevity of the population, high expectations of medical treatment, and the impossibility of trauma prediction make treatment of retinal tears advisable. The advances in surgical equipment and techniques reduce the likelihood of complications. The short recovery period makes treatment acceptable to active and working patients. RP

REFERENCES

1. Teng, C. and H. Katzin (1952) An anatomic study of the periphery of the retina: I. Nonpigmented epithelial cell proliferation and hole formation. Am J Ophthalmol. 32: p. 1237-1248.
2. Pollak, A. and M. Oliver (1981) Argon laser photocoagulation of symptomatic flap tears and retinal breaks of fellow eyes. Br. J. Ophthalmol. 65: p. 469-72.
3. Kazohaya, M. (1995) Prophylaxis of retinal detachment. Semin Ophthalmol. 10(1): p. 79-86.
4. Wilkinson, C. (2000) Evidence-based analysis of prophylactic treatment of asymptomatic retinal breaks and lattice degeneration. Ophthalmology. 107(1): p. 12-15.
5. Combs, J. and R. Welch (1982) Retinal breaks without detachment: natural history, management, and long-term follow-up. Trans Am Ophthalmol Soc. 80: p. 64-97.
6. Byer, N. (1996) What happens to untreated aymptomatic retinal breaks, and are they affected by posterior vitreous detachments? Am J Ophthalmol. 105(6): p. 1045-50.
7. Morse, P. and R. Eagle (1975) Pigmentation and retinal breaks. Am J Ophthalmol. 79(2): p. 190-193.
8. Davis, M.D. (1974) Natural History of Retinal Breaks Without Detachment. Arch ophthalmol. 92: p. 183-94.
9. Robertson, D. and H. Buettner (1977) Pigmented preretinal membranes. Am J Ophthalmol. 83: p. 824-9.
10. Glaser, B., et al. (1993) Cryotherapy during surgery for giant retinal tears and intravitreal dispersion of viable retinal pigment epithelial cells. Ophthalmology. 100(4): p. 466-70.
11. Benson, W.B. (1977) Prophylactic Therapy of Retinal Breaks. Survey of Ophthalmology. 22(1): p. 41-7.
12. Govan, J.A. (1981) Prophylactic circumferential cryopexy: a retrospective study of 106 eyes. Br. J. Ophthalmol. 65: p. 364-70.