What is aphakic glaucoma?

Aphakic Glaucoma

Aphakic glaucoma is a form of secondary open-angle glaucoma that develops in eyes without a natural crystalline lens (aphakia), most commonly occurring as a complication following cataract surgery, particularly when complicated by posterior capsule rupture or in pediatric cases. 1, 2

Definition and Clinical Characteristics

Aphakic glaucoma represents a distinct clinical entity characterized by:

• Elevated intraocular pressure (IOP) in the absence of the natural crystalline lens, typically presenting with an open anterior chamber angle on gonioscopy 3, 4
• Most cases manifest as open-angle glaucoma, though angle-closure mechanisms can occur secondary to pupillary block or postoperative complications 2
• The condition can be classified temporally: early aphakic glaucoma (within 6 weeks postoperatively) versus late aphakic glaucoma (occurring at any time thereafter) 2

Epidemiology and Risk Factors

The incidence and risk profile varies significantly by patient population:

• In pediatric aphakic patients, the incidence ranges from 15% to 45%, with higher rates in small eyes and infants undergoing surgery before 4 weeks of age 1
• In adult aphakic patients following complicated cataract surgery, glaucoma represents a significant long-term complication requiring ongoing surveillance 4
• Risk factors include: postoperative shallow or empty anterior chambers, wound fistula, choroidal detachment, inflammation, and epithelial downgrowth 2

Pathophysiologic Mechanisms

Multiple mechanisms can produce elevated IOP in aphakic eyes:

• Pupillary block and angle closure represent the most serious mechanisms, often emanating from postoperative shallow anterior chambers 2
• Trabecular meshwork dysfunction leads to open-angle glaucoma, the most common presentation 3, 1
• Inflammatory processes, alpha-chymotrypsin exposure during surgery, iris cysts, and epithelial downgrowth can all contribute 2
• Macular edema, including cystoid macular edema, has been reported during treatment with prostaglandin analogs in aphakic patients, as these medications should be used with caution in patients without an intact posterior capsule 5

Clinical Course and Prognosis

The natural history of aphakic glaucoma is generally unfavorable:

• Despite careful monitoring and treatment, many children with aphakic glaucoma have poor vision, poor glaucoma control, and ultimately become blind 1
• In adult aphakic patients, mean IOP can decrease from 26.21±13.86 mmHg to 18.14±9.63 mmHg with treatment, though mean vertical cup/disc ratio progresses from 0.69±0.25 to 0.78±0.24 despite therapy 4
• Prevention of glaucomatous optic neuropathy in aphakic patients is challenging both medically and surgically, with progression of glaucomatous disc changes occurring even when IOP is reduced 4

Management Approach

Medical Management

• Most aphakic glaucoma patients (approximately 90%) are initially managed with topical glaucoma medications, though the mean number of medications typically increases over time (from 1.41±1.27 to 2.07±1.04) 4
• Prostaglandin analogs like latanoprost should be used with caution in aphakic patients due to increased risk of macular edema 5

Surgical Management Algorithm

When maximal medical therapy fails, the following surgical approach is recommended:

1. Laser trabeculoplasty (if angle is open): In aphakic patients with mean preoperative IOP of 25 mmHg, 80% achieved IOP <22 mmHg for an average of 8 months without significant complications 3

2. Trabeculectomy with mitomycin C (if laser fails or angle is extensively closed): Success rates of 62% for IOP control ≤21 mmHg at mean 26-month follow-up, though only 4 of 15 patients (27%) achieved success at 9 months in another series 3, 6

3. Glaucoma drainage devices (Seton implants): These show better short-term and more promising long-term success rates compared to trabeculectomy, with success rates ranging from 14% to 44% 1

4. Cyclodestructive procedures (cyclocryotherapy or cyclophotocoagulation): Reserved for refractory cases, though associated with unpredictable vision loss (14-20% severe visual loss) and phthisis bulbi in 11% of cyclocryotherapy cases 3, 6

Critical Clinical Pitfalls

• Diagnostic difficulties in children may lead to delayed treatment, requiring examinations under general anesthesia for adequate monitoring 1
• Surgery alone is typically insufficient to control IOP, with most patients requiring additional glaucoma medications even after surgical intervention 4
• The complication of decreased visual acuity following surgery is significant, though not always directly related to the surgical procedure itself 3
• Lifelong monitoring is mandatory for all aphakic patients, as glaucoma can develop at any time following cataract surgery 1, 4