Postoperative Management of Nonpenetrating Glaucoma Surgery

Introduction

There is enough evidence in literature to suggest that NPGS, nonpenetrating glaucoma surgery, is safer than other glaucoma surgical procedures, and with a faster rehabilitation profile, both visual and otherwise. The retained trabeculo-Descemetic membrane (comprising the anterior and posterior trabecular meshwork, and Descemet's membrane) results in residual outflow resistance thereby minimizing complications like hyphema, inflammation, hypotony-related complications, postoperative infections and cataract formation. Despite this, the first few postoperative weeks are crucial for the success of NPGS, as in the case of any other glaucoma surgical procedure.

All current glaucoma surgical procedures are a paradox. They rely on the body's healing response to provide just enough scarring to prevent over-filtration, while at the same time maintaining the patency of the filtering conduit.

The main aim of postoperative care, therefore, after NPGS is to fight against excessive normal body response to trauma, in order to avoid bleb failure. The sites of scarring which may impact end results of NPGS include: trabeculo-Descemet's membrane, intrascleral space, sclera, episclera, Tenon's capsule, and conjunctiva. Managing of complications that may arise either in the early or late postoperative period, constitutes an important part of postoperative care.

Assessment Parameters and Regimen

The following regimen is recommended as a guideline, but the postoperative follow-up protocol must be customized to each individual. It is good clinical practice to see the patient a few hours after surgery if the hospital resources in terms of time and man power permit. If not, the first follow-up visit should be scheduled for the first postoperative day, and a comprehensive eye examination is mandatory at this time. Special care should be taken to monitor the IOP, bleb and anterior chamber.

After this, the patient is seen after a week, and then after two weeks. The patient should then be monitored at the 2nd, 3rd and 6th months, and, finally every 6 months with visual field examinations and retinal nerve fiber/optic nerve head imaging once a year; or as deemed fit, depending on the severity of glaucoma.

Each of the following parameters must be assessed and recorded at each visit:

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  Uncorrected and best corrected visual acuity.

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  Filtering bleb: extent, height, vascularity of the conjunctiva, presence of conjunctival microcysts, presence of wound leak or oozing (Siedel's test mandatory).

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  Anterior chamber: depth, inflammation, hyphema.

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  Cornea: clarity, Descemet's membrane integrity, astigmatism.

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  IOP.

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  Optic disc, macula, and retina.

Gonioscopy may be performed to visualize the TDM to assess its thickness and size; any holes, synechiae or iris herniation must be documented ( Fig. 100-1 ).

This regimen is given as a guideline, and the surgeon should remain flexible and individualize his or her follow-up protocol to specific cases and scenarios.

Postoperative Medication

The routine postoperative medication following NPGS is to prevent infection, inflammation and the consequent excessive scarring.

Corticosteroids are used to inhibit postoperative inflammation in the anterior segment, thereby reducing the rate of conjunctival epithelialization, collagen synthesis and angiogenesis. Prednisolone acetate 1.0% drops may be administered from the day of surgery. Usually, the drops are given four to six times a day for the first two weeks, and then rapidly tapered off over the next four weeks; some surgeons, however, would insist on corticosteroids for up to 3 months postoperatively. It must be kept in mind that these steroid drops can result in a steroid-induced IOP rise.

A broad-spectrum antibiotic, in accordance with local antibiotic prophylaxis policies, is recommended as a safeguard against postoperative bleb infection and endophthalmitis, for a period of one to four weeks. In our clinic, we currently use moxifloxacin eyedrops three times a day, for up to 4 weeks.

The beneficiary effect of non-steroidal anti-inflammatory drugs (NSAIDs) such as indometacin and diclofenac on postoperative inflammation and pain has been documented, and these may be prescribed as a substitute for topical steroids in steroid-responders.

As a routine, all our patients get topical NSAIDs three times a day for 2 months, after the cessation of corticosteroids.

Instructions to the Patient

Apart from the postoperative medication, the patient must be instructed about precautions and postoperative care. These include:

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  The patient is instructed to avoid full physical activity (heavy lifting or straining) during the period when IOP is below physiological levels, and generally speaking for at least two weeks after surgery.

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  The patient is instructed to not rub the eyes; wearing of eye shields is not advised routinely, but may be required for the elderly, especially at night.

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  The patient must avoid contact sports and trauma to the eye for at least four weeks.

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  Some patients may benefit from limitation of physical activities involving forward bending. For example the patient is instructed to not bend steeply to search for his slippers.

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  The patient must be instructed to clean the eyes with sterilized cotton and water, at least twice a day. Any deposits, especially since most steroid eye drops are dispensed as suspensions, must be cleaned gently with sterile cotton.

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  The patient must be instructed to continue with the prescribed anti-glaucoma medication in the eye which has not had surgery, which is sometimes a message lost in communication.