1 New Options in the Treatment of Glaucoma A 71–year-old woman with a history of primary open-angle glaucoma with severe optic nerve and visual field damage presented with uncontrolled intraocular pressure (IOP) on maximum tolerated medications. The cup-to-disk (C/D) ratio was 0.9 to 0.95 with superior and inferior thinning of the rim and corresponding dense superior and inferior arcuate scotomas. Despite this, visual acuity was 20/30, but 20/400 in the fellow eye, making her functionally monocular. The IOP was 19 to 21 on three topical medications, including a prostaglandin analogue, β-blocker, and carbonic anhydrase inhibitor. The patient had an allergy to α-agonists. The visual field was showing slow but steady progression over a 3-year period, with a mean deviation slope of –1.6. After the patient provided appropriate informed consent, the decision was made to proceed with a trabeculectomy with mitomycin. The surgery was uneventful, and after 3 months of follow-up the IOP was 12 to 14 on no glaucoma medications. The conjunctival bleb was diffuse, but cystic and avascular at the limbus. Three years following surgery, the patient experienced a decline in vision, with pain and redness. She was seen emergently and diagnosed with blebitis and possible endophthalmitis due to the presence of vitreous cells. The vision was 20/400, and a small hypopyon was present with a mild amount of purulent discharge. The patient underwent emergent pars plana vitrectomy with intravitreal fortified antibiotics (gentamicin and Ancef). A culture was taken and eventually grew Streptococcus species that was sensitive to the treating antibiotics. Despite this, the vision dropped to light perception, and 2 weeks later the patient underwent repeat vitrectomy, this time via endoscopic guidance because the cornea was opacified. The endoscopic view demonstrated dense fibrinous purulent material throughout the vitreous cavity. This was removed, except for a dense plaque that was adherent to the macula. Despite eventual control of the infection, the vision remained at light perception only. A 78-year-old Caucasian woman with primary open-angle glaucoma and moderate to severe optic nerve damage and visual field loss presented with uncontrolled IOP on maximum tolerated medications. The visual acuity was 20/70 with a 3+ nuclear sclerotic cataract (Fig. 1.1). The IOP was 24 mm Hg on a prostaglandin analogue and fixed combination of β-blocker and carbonic anhydrase inhibitor. The patient underwent surgery with a Baerveldt glaucoma implant 350 (Abbott Medical Optics, Santa Ana, CA) and combined phacoemulsification cataract extraction. Six weeks after surgery, the ligature occluding the tube opened and the patient developed hypotony and a flat anterior chamber. Ultrasonography demonstrated a mixed choroidal effusion and hemorrhage, without central touch but with a decrease in vision to 20/400 and an IOP of 25. The patient was placed on topical steroids and atropine 1%. Despite medical treatment and eventual resolution of the choroidal fluid, the anterior chamber remained very shallow. The patient was lost to follow-up for 2 months, and returned with corneal decompensation and bullous keratopathy, with an IOP of 5. A tube exchange was performed with removal of the Baerveldt implant and placement of an Ahmed glaucoma valve (New World Medical, Rancho Cucamonga, CA) to increase the IOP to more physiological levels. The patient refused further surgery until 2 years later, when a penetrating keratoplasty was performed. At last follow-up, the IOP was 15 on a fixed combination of β-blocker and carbonic anhydrase inhibitor, but the cornea transplant had rejected and vision was now light perception (Fig. 1.2). Traditional glaucoma filtration surgery relies on the shunting of aqueous humor to the subconjunctival space, either through a perilimbal scleral opening (as in trabeculectomy) or through a tube shunt to an external reservoir in the equatorial area. Techniques have advanced in these procedures so that they are quite successful in lowering the IOP with an improving safety profile. However, as these unfortunate case presentations exhibit, significant postoperative risks exist, such as late-onset bleb infection or endophthalmitis, hypotony maculopathy, choroidal effusion or hemorrhage, flat anterior chamber, corneal damage, diplopia, and cataract formation.1 These risks may be acceptable to a patient with advanced glaucoma and rapidly progressing visual field loss to prevent blindness, but they are not appropriate for a patient with mild to moderate disease or one who wishes to reduce the medication burden. Recently, a new category of glaucoma surgery has developed—minimally invasive glaucoma surgery (MIGS),2 also called microincisional and microinvasive glaucoma surgery. The basic tenets of MIGS procedures are an ab interno surgical approach that uses a small incision and spares the conjunctiva and sclera (Table 1.1). The surgery should be minimally traumatic with minimal tissue disruption. The safety profile is excellent, especially as compared with more traditional glaucoma filtration surgery. Recovery should be rapid, with good preservation of vision. The IOP is lowered to “physiological levels” or usually in the mid-teens (Table 1.2). When conceptualizing existing and new glaucoma surgical techniques, it is helpful to categorize them by the method of action. In this book, we shall elucidate four different pathways by which we can manipulate aqueous movement to lower the IOP in a minimally invasive fashion: trabecular, or Schlemm’s canal; the suprachoroidal space; aqueous humor production; and the subconjunctival space. Fig. 1.3 illustrates different ways that the canal or the suprachoroidal space can be altered to increase outflow.
Case Presentations
Case 1
Case 2
Introduction to the Novel Glaucoma Procedures
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