49.1General Considerations

49.1.1 Etiology

Macular edema may be caused by a focal abnormality such as traction (see Chap. 50), a local condition such as cataract extraction, systemic diseases such as diabetes, and a combination of local and systemic abnormalities such as uveitis. The list of possible causes is very long.

If a deÞnite cause is identiÞed, it should be the primary target of the treatment. This basic principle, however, still leaves open the question of how best to directly treat the edema itself.

49.1.2 Indications for Treatment: Surgical or Nonsurgical?

The answer to this crucial question is controversial on several levels. There is little consensus even among ophthalmologists, and therapeutic decisions are increasingly inßuenced by insurance companies, health authorities, drug manufacturers, or even politicians (see Sect. 4.6 and Chap. 43).1 I raise only a few important points to help guide the decision-making process.

¥Focal (grid) laser, laser maculopexy (see Fig. 30.2), and panretinal laser (see Sect. 30.3.2), alone or in combination with medical and/or surgical therapy, should always be considered in conditions such as diabetes or vein occlusion.

1 Just think about the protracted battle fought in many countries over whether to use ÒLucentis or Avastin?Ó.

F. Kuhn, Vitreoretinal Surgery: Strategies and Tactics,

DOI 10.1007/978-3-319-19479-0_49

¥Intraocular injections represent the Þrst line of treatment today in most cases, but they are a temporary solution for a permanent problem in a disease such as diabetes. Repeated injections must be given over extended periods of time, which involve, among others, the following:

ÐBurden on the patient: continual seesawing of the visual function as well as mandated returns for an intraocular procedure to a medical facility. The physical and psychological implications of this rollercoaster must not be neglected (person vs tissue being treated; see Sect. 5.1).

ÐBurden on the facility2: the need to organize the time, personnel, venue, materials (ordering and storage), patient scheduling, cash ßow and reimbursement etc. The number of patients and injections seems to never stop increasing as more drugs come to the market and the indication list widens.

¥No Òlevel 1 evidenceÓ study looked at the results of surgery vs a drug. All studies evaluated drugA vs drug B, their dosing, or their use based on the presenting VA level.

¥The risk and severity of complications are undoubtedly greater with surgery than with an injection. It is, however, false to compare the complication risk between surgery vs a single injection. No patient receives a single intravitreal injection for ME.

¥Surgery is much more difÞcult to unequivocally deÞne than a drugÕs dose. If the surgical procedure proves to be ineffective, the blanket claim that Òsurgery does not workÓ is no more correct than suggesting that Òdrugs do not workÓ if a single medication is found ineffective.3 The conclusion, correctly, is that Òthis kind of surgery does not workÓ or that Òsurgery at this late stage of the disease does not work.Ó

¥Surgery should not be considered as a last resort.4 The prognosis is best when the intervention is done before the macula suffers irreversible damage.

ÐSurgery, if done early5 and well, has a very good chance of being a one-time cure.

ÐIf surgery fails, all other treatment options are still available.

49.2Surgical Technique6

¥If logistically feasible, dry the macula preoperatively.7

¥Do a vitrectomy with TA-conÞrmed detachment of the posterior hyaloid.

¥Stain and remove the ILM in the macular area.8

2It all can be summarized by the term ÒlogisticsÓ: the detailed coordination of a complex operation involving many people, facilities, and supplies, as well as their Þnancing.

3No sane person would declare that, based on his experience driving a Fiat Uno, Òcars cannot exceed a speed of 200 km/h.Ó Everybody knows that driving a Porsche 911 is an entirely different matter.

4When all else has failed.

5Surgery is considered as the initial treatment. The otherwise progressive condition is in its early stage and the vision is still good. In my own large series of patients who underwent PPV with ILM peeling and laser maculopexy, none required treatment for macular edema postoperatively if their visual acuity was 0.6 or greater preoperatively.

6See also Chap. 50 and Sect. 52.2. The technique described here is most applicable in conditions such as diabetes, vein occlusion, uveitis etc.

7Intravitreal anti-VEGF or TA injection.

8See also Sects. 32.1 and 34.3.

Pearl

The retina in an eye with chronic macular edema is unhealthy: you must be much more delicate with your maneuvers than if the tissue were healthy (e.g., macular hole is the indication for ILM peeling).

ÐStart the peeling well away from the fovea (see Fig. 49.1).

ÐBe very slow when peeling over the fovea, especially if it has large cysts9: the top of the cyst is extremely thin, and you must avoid unrooÞng it.10

1

c

3 + 2

Fig. 49.1 Peeling the ILM in an eye with severe diabetic macular edema (this is my personal technique). (a) The red area shows the extent of the edema. (b) The initial peel is across the fovea (1), starting superiorly. (c) This is followed by two semicircles (2, 3). It is not necessary to peel the entire area where edema is present, especially toward the temporal side

9The cysts appear to the surgeon as gray circles (see Fig. 49.2).

10If it does happen, a small amount of somewhat viscous ßuid is seen entering the vitreous cavity.

ÐIf the ILM is very adherent, it may elevate the retina slightly (tenting), and a Þne white line is seen along the separation border between ILM lifted and still in situ (see Fig. 49.3). If such a white line is present, you should proceed even more cautiously, and the vector of the peeling should be even more parallel to the retina (see Fig. 49.4).

Fig. 49.2 Intraretinal cysts in macular edema. The cysts containing viscous ßuid appear as dark circles, especially visible temporal to the fovea in this intraoperative image

Fig. 49.3 Peeling the adherent ILM over an area of macular edema. The underlying retina is more fragile than in an eye without edema. The retina often tents as the forceps is pulling on the ILM; this is detected by the surgeon as a white line that snakes perpendicular to the main vector of the peeling. Such an image should make the surgeon even more careful to avoid tearing the retina or unrooÞng a cyst

a

b

Fig. 49.5 Peeling the ILM over a convex surface (cross-sectional, schematic representation). (a) The normal macular contour is concave; when the ILM is peeled toward the foveola (centripetal direction), the tip of the forceps is moved further away from the surgeon (ÒdownhillÓ; black arrows). (b) In severe edema, the macular contour is akin to an elevation. When the ILM is peeled toward the foveola, the tip of the forceps must be moved toward/closer to the midvitreous cavity; as seen from the surgeonÕs perspective, peel ÒuphillÓ (gray arrows). Since the surgeon views this from above, the change in the actual geography of the macula is difÞcult to appreciate. In a macula with a foveal thickness of 600 μ, the ILM is ~4× closer to the surgeon than it would be in an eye with normal retinal thickness