Free Board Certified Ophthalmologist Glaucoma Management Questions and Answers — Questions and Answers
Question 1: A 65-year-old male with moderate primary open-angle glaucoma (POAG) has been using latanoprost for several years, but his intraocular pressure (IOP) is no longer at target. You decide to switch him to latanoprostene bunod. What is the additional mechanism of action provided by latanoprostene bunod compared to latanoprost?
- It increases aqueous production.
- It enhances uveoscleral outflow only.
- It increases trabecular meshwork outflow via nitric oxide donation. (Correct answer)
- It constricts the ciliary muscle to decrease aqueous inflow.
Correct answer: It increases trabecular meshwork outflow via nitric oxide donation.
Latanoprostene bunod is a dual-action drug. It is metabolized into latanoprost acid, which increases uveoscleral outflow like other prostaglandin analogs, and butanediol mononitrate. The butanediol mononitrate component releases nitric oxide (NO), which relaxes the trabecular meshwork and Schlemm's canal, thereby increasing conventional (trabecular) outflow.
Question 2: A 58-year-old woman with newly diagnosed, mild primary open-angle glaucoma (POAG) and ocular hypertension is treatment-naïve. According to the 6-year results of the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial, which of the following is the most appropriate initial treatment to offer this patient for better long-term disease control and a lower rate of progression?
- A topical beta-blocker
- Selective Laser Trabeculoplasty (SLT) (Correct answer)
- A topical prostaglandin analog
- Immediate trabeculectomy
Correct answer: Selective Laser Trabeculoplasty (SLT)
The LiGHT trial's 6-year results demonstrated that initial treatment with Selective Laser Trabeculoplasty (SLT) was associated with better long-term disease control, a slower rate of visual field progression, and a reduced need for subsequent incisional surgery compared to initial treatment with IOP-lowering eye drops. For a treatment-naïve patient, SLT is therefore recommended as a first-line intervention.
Question 3: Which of the following patient factors is considered a significant, non-IOP-related risk factor for the progression of glaucomatous damage in a patient with established primary open-angle glaucoma?
- High myopia
- Thick central corneal thickness (>580 microns)
- Systemic hypertension
- Low corneal hysteresis (Correct answer)
Correct answer: Low corneal hysteresis
Low corneal hysteresis (CH) has been identified as a strong and independent risk factor for glaucoma progression, separate from intraocular pressure and central corneal thickness. CH reflects the cornea's biomechanical ability to absorb and dissipate energy, and lower values suggest a less resilient optic nerve. While high myopia and systemic vascular conditions are associated with glaucoma, low CH is a more direct biomechanical risk factor for progression.
Question 4: A 45-year-old patient with chronic anterior uveitis develops elevated intraocular pressure (IOP) refractory to topical beta-blockers and carbonic anhydrase inhibitors. The inflammation is currently well-controlled on a topical steroid. Which of the following would be the most appropriate next step in surgical management?
- Argon Laser Trabeculoplasty (ALT)
- Trabeculectomy with mitomycin C
- Implantation of a glaucoma drainage device (tube shunt) (Correct answer)
- Transscleral cyclophotocoagulation (CPC)
Correct answer: Implantation of a glaucoma drainage device (tube shunt)
In uveitic glaucoma, particularly with active or chronic inflammation, glaucoma drainage devices (tube shunts) are often the preferred first-line surgical intervention. Trabeculectomy has a higher failure rate due to inflammation-induced fibrosis, and laser trabeculoplasty can exacerbate inflammation. Cycloablative procedures are typically reserved for refractory cases as a last resort due to the risk of worsening inflammation and hypotony.
Question 5: A 72-year-old patient with advanced glaucoma undergoes a trabeculectomy with mitomycin C. Three weeks post-operatively, his IOP is 2 mmHg, the anterior chamber is shallow, and fundus examination reveals choroidal effusions. The bleb is diffuse but there is no evidence of a leak on Seidel testing. What is the most likely cause of this patient's hypotony?
- Aqueous misdirection (malignant glaucoma)
- Pupillary block
- Overfiltration through the scleral flap (Correct answer)
- Bleb failure due to scarring
Correct answer: Overfiltration through the scleral flap
Post-operative hypotony with a shallow anterior chamber, choroidal effusions, and a diffuse, non-leaking bleb in the early period after a trabeculectomy is characteristic of overfiltration. The scleral flap is allowing too much aqueous to exit the anterior chamber. Aqueous misdirection would typically present with a high IOP. Pupillary block is unlikely in the presence of a patent iridectomy. Bleb failure would lead to high IOP.
Question 6: A 68-year-old glaucoma suspect is being monitored with annual spectral-domain OCT of the retinal nerve fiber layer (RNFL). According to glaucoma progression analysis software and established research, which of the following changes in average RNFL thickness would be most suspicious for true glaucomatous progression, exceeding expected age-related thinning?
- A decrease of 0.5 µm over one year
- A decrease of 2 µm over five years
- A decrease of 5 µm over two years (Correct answer)
- An increase of 3 µm over one year
Correct answer: A decrease of 5 µm over two years
While age-related RNFL thinning occurs at a rate of approximately -0.5 µm/year, glaucomatous progression is marked by a faster rate of loss. An event-based change of 5 µm or more is considered suspicious for progression. A decrease of 5 µm over two years (-2.5 µm/year) is significantly faster than age-related loss and highly indicative of true glaucomatous progression, warranting consideration for treatment initiation.
Free Board Certified Ophthalmologist Glaucoma Management Questions and Answers
A 65-year-old male with moderate primary open-angle glaucoma (POAG) has been using latanoprost for several years, but his intraocular pressure (IOP) is no longer at target.
You decide to switch him to latanoprostene bunod.
What is the additional mechanism of action provided by latanoprostene bunod compared to latanoprost?