Introduction

Open angle glaucoma (OAG) is a multifactorial optic neuropathy, with an increasing prevalence. The prevalence of OAG in India is 12.9%. Elevated intraocular pressure (IOP) is the key risk factor for OAG. Nevertheless, many patients with glaucoma progress despite reasonable control of IOP. Studies have demonstrated that ischemia in the optic nerve and dysfunctional vascular regulation lead to glaucomatous damage in many patients. Ocular perfusion pressure (OPP) along with blood flow have a critical role in the pathogenesis of glaucoma. Similarly, color doppler imaging (CDI) studies have indicated that low ocular blood flow (OBF) is also involved in glaucoma progression and visual field loss. Improving the ocular blood flow may thus improve the management of progressive glaucoma.

Aim

To determine the efficacy of dorzolamide 2% in improving retrobulbar blood flow in an Indian setting.

Patient Profile

• Treatment naïve patients with mild-to-moderate OAG or normal tension glaucoma in at least one eye (age ≥40 years, n=38 eyes of 19 patients).
• The severity of glaucoma damage in patients was further categorized as follows:
  • Mild: Definite optic disk or retinal nerve fiber layer (RNFL) abnormalities consistent with glaucoma with a normal visual field [as tested with standard automated perimetry (SAP)]
  • Moderate: Definite optic disk or RNFL abnormalities consistent with glaucoma, along with visual field abnormalities in one hemifield that are not within 5° of fixation as tested with SAP
  • Severe: Definite optic disk or RNFL abnormalities consistent with glaucoma, and visual field abnormalities in both hemifields and/or loss within 5° of fixation in at least one hemifield as tested with SAP
  • Indeterminate: Definite optic disk or RNFL abnormalities consistent with glaucoma, inability of the patient to perform visual field testing, unreliable/uninterpretable visual field test results, or visual fields not performed yet.
• The study also included 24 healthy individuals with no ocular abnormality, and having normal optic disks, and IOP <20 mmHg in both eyes for baseline OBF evaluation.

Methods

Study Design

• An interventional pilot study conducted across multiple eye hospitals in Chennai, India.

  Assessments

• Baseline OBF measurements using CDI were performed for all glaucoma patients.
• Baseline OPP was calculated for all the study participants.
• Baseline IOP measurements

Treatment Strategy

• Patients (n=19, 38 eyes) received 1 drop of dorzolamide 2% thrice daily for 12 weeks.

  Outcomes

  Primary Outcomes

• The mean changes in the CDI parameters of the retrobulbar vessels
• The mean change in OPP post-treatment

Secondary Outcome

• The mean change in the IOP

  Safety Outcome

• Incidence of adverse events

  Results

• The mean age of the glaucoma patients was 59.63 years.
• Glaucoma patients displayed significantly reduced baseline OPP compared to healthy subjects (P = 0.002) (Table 1)

  	Glaucoma Patients	Healthy Subjects	P value
  No. of patients	19 (38 eyes)	24 (24 eyes)	N/A
  Mean IOP (mmHg)	16.05	12.5	-
  Mean OPP	46.63	55.61	0.002

   

   

• At 12 weeks glaucoma patients treated with dorzolamide had a significant improvement in OPP from baseline (P<0.001) (Table 2).
• Dorzolamide-treated patients also exhibited a significant increase in end diastolic velocity (EDV) in all major ophthalmic arteries like ophthalmic artery (OA; P <0.001), central retinal artery (CRA; P =0.04), and short posterior ciliary artery (SPCA; P =0.0075) (Table 2).
• The IOP (P = 0.007) reduced significantly, post-treatment with dorzolamide (Table 2).

Table 2: Change in the various clinical parameters during the study period

• No adverse events were reported during the study.

  Conclusions

• Indian glaucoma patients have significantly lower OPP compared to healthy subjects.
• Glaucoma patients treated with dorzolamide 2% had a significant improvement in hemodynamic parameters such as the EDV and OPP in major ophthalmic arteries.
• Dorzolamide seems to be a promising agent for treating Indian patients with OAG.

Indian J Ophthalmol 2022;70:4164-4167.