Review of recent publications of the Advanced Glaucoma Intervention Study

Glaucoma Drug Prescription Pattern in North India: Public vs Private Sector Hospitals

Background

Glaucoma is an optic neuropathy associated with characteristic structural damage to the optic nerve and associated visual dysfunction that may be caused by various pathological processes. A number of pharmacological agents are used to reduce the intraocular pressure (IOP), involving the usage of two or three medications concurrently. Literature is sparse regarding prescription patterns of antiglaucoma drugs, especially regarding variability in public sector vs private sector hospitals. Drug utilization studies can add insight for crafting rational, affordable, and ocular surface friendly prescriptions.

Aim

This study assessed the prescription pattern in glaucoma patients of a public sector, tertiary care hospital vs a private sector tertiary care hospital.

Materials and methods

In this retrospective study, pertinent data of diagnosed and labeled glaucoma patients were reviewed. Data collected included demographic details, type of glaucoma, number and nature of drugs prescribed, whether innovator or generic drugs were prescribed, if fixed-drug combinations (FDCs) and preservative-free formulations were prescribed. The prescription patterns between the two sectors were compared, as were the prescription patterns between primary open-angle glaucoma (POAG) and primary angle-closure disease (PACD).

Results

A total of 336 prescriptions were evaluated (216 from public sector, group I; 120 from private sector, group II). Travoprost 0.004% was the most prescribed antiglaucoma medication in both group I (30.09%) and group II (38.33%). Brimonidine and brinzolamide (14.17%) was the most prescribed combination in group II, while Brimonidine with Timolol (7.87%) in group I. In group I, Timolol and Travoprost were the most prescribed medications for both PACD and POAG.

Conclusion

This study showed that both public sector as well as private sector tertiary care centers prescribe antiglaucoma medications in tune with current principles of rational drug use. Preservative-free drugs were preferred in both the groups for better adherence.

How to cite this article

Bhartiya S, Ichhpujani P, Parmar UPS, et al.Glaucoma Drug Prescription Pattern in North India: Public vs Private Sector Hospitals. J Curr Glaucoma Pract 2024;18(1):16-22.

An hypothesis on pressure transmission from anterior chamber to optic nerve

Few studies have characterized how pressure in the anterior chamber (AC) of the eye is transmitted via the vitreous to the vitreous-ganglion cell interface. We are aware of only one study that simultaneously measured the pressures in the AC and vitreous humor; and of only one study that simultaneously measured the pressures in the AC and the suprachoroidal space (SCS). The pressure in the AC is defined as the intraocular pressure (IOP), which when elevated beyond statistically normal limits is a recognized risk factor for glaucoma, a malady best described as an optic neuropathy with degeneration and eventual death of the retinal ganglion cells (GC's) and highly characteristic changes in the optic nerve head (ONH). Most investigators currently believe that the prevalent risk factor for GC apoptosis is ocular hypertension, but no one has demonstrated how an increase in IOP in the AC is transmitted to the GC's. In patients with primary open angle glaucoma, the pressure in the AC increases due to an increase in the resistance of the trabecular meshwork (TM) outflow pathway. We questioned how such increased pressure in the AC would be transmitted to the GC to produce the changes in the ONH seen in glaucoma. Based on our preliminary data and purview of the literature, we hypothesize that a pressure increase originating in the AC is likely transmitted via both the SCS and the vitreous, with transmission via the former pathway probably most efficient in affecting the GC. Independently of the mechanism that produces GC apoptosis, the ones that are first affected, as repeatedly shown by visual field tests, are the most peripheral ones; i.e., those whose axons are the most external as they form the ONH and enter the lamina cribrosa. There are no published reports explaining this peculiarity. The dogma is that the pressure transmitted via the vitreous is higher at the periphery because it is transmitted across a shorter distance, since the vitreous acts as a buffer that absorbs part of the pressure being transmitted. We propose that IOP is not only transmitted via the vitreous but also via the SCS. Increases in IOP could be efficiently applied via the SCS to the most external axons of the ONH as they leave the eye. Our hypothesis can also explain low-tension glaucoma in which the most peripheral GC's are also affected first, because pressure is transmitted without decay due to a reduced uveoscleral (UVS) flow.

The early flat anterior chamber after trabeculectomy: a randomized, prospective study of 3 methods of management

PURPOSE

To evaluate prospectively 3 different approaches to the management of a flat anterior chamber (FAC) because of overfiltration in the early postoperative period after trabeculectomy.

MATERIALS AND METHODS

Thirty-six eyes diagnosed with a FAC with total iridocorneal touch, but no lenticular touch (grade II) because of overfiltration in the first 14 days after trabeculectomy were randomized prospectively into 3 groups: group 1--anterior chamber reformation with viscoelastic substance; group 2--anterior chamber reformation with balanced salt solution and concurrent drainage of choroidal effusion; and group 3--pharmacologic therapy with atropine, phenylephrine, and in select cases oral acetazolamide. Outcome measures were visual acuity, amount of intraocular pressure (IOP) reduction, and achievement of predetermined target IOP.

RESULTS

Treatment group 2 had a greater number of eyes with acuity decline of two or more lines relative to group 3 (P=0.04). Group 1 had more eyes with acuity decline of two or more lines relative to group 3, but this was not significant (P>0.05).

CONCLUSIONS

For grade II FACs because of overfiltration in the early postoperative period after trabeculectomy, reformation of the anterior chamber with drainage of choroidal effusion may be associated with greater long-term trabeculectomy success, but is associated with greater visual acuity loss relative to medicinal therapy alone. Reformation with viscoelastic resulted in a trend toward lowest final IOP in comparison to medicinal therapy alone.

Susceptibility to glaucoma: differential comparison of the astrocyte transcriptome from glaucomatous African American and Caucasian American donors

Comparison of gene expression in normal and glaucomatous eyes from Caucasian American and African American donors reveals differences that might reflect different susceptibility to glaucoma.

Background

Epidemiological and genetic studies indicate that ethnic/genetic background plays an important role in susceptibility to primary open angle glaucoma (POAG). POAG is more prevalent among the African-descent population compared to the Caucasian population. Damage in POAG occurs at the level of the optic nerve head (ONH) and is mediated by astrocytes. Here we investigated differences in gene expression in primary cultures of ONH astrocytes obtained from age-matched normal and glaucomatous donors of Caucasian American (CA) and African American (AA) populations using oligonucleotide microarrays.

Results

Gene expression data were obtained from cultured astrocytes representing 12 normal CA and 12 normal AA eyes, 6 AA eyes with POAG and 8 CA eyes with POAG. Data were normalized and significant differential gene expression levels detected by using empirical Bayesian shrinkage moderated t-statistics. Gene Ontology analysis and networks of interacting proteins were constructed using the BioGRID database. Network maps included regulation of myosin, actin, and protein trafficking. Real-time RT-PCR, western blots, ELISA, and functional assays validated genes in the networks.

Conclusion

Cultured AA and CA glaucomatous astrocytes retain differential expression of genes that promote cell motility and migration, regulate cell adhesion, and are associated with structural tissue changes that collectively contribute to neural degeneration. Key upregulated genes include those encoding myosin light chain kinase (MYLK), transforming growth factor-β receptor 2 (TGFBR2), rho-family GTPase-2 (RAC2), and versican (VCAN). These genes along with other differentially expressed components of integrated networks may reflect functional susceptibility to chronic elevated intraocular pressure that is enhanced in the optic nerve head of African Americans.

A novel index for predicting intraocular pressure reduction following cataract surgery

AIM

The results of a study designed to investigate the predictive value of preoperative anterior chamber depth (ACD) and intraocular pressure (IOP) are reported. The relation between these factors and their effect on the reduction in IOP following phacoemulsification cataract surgery was also studied.

METHODS

The ACD and IOP were prospectively measured in 103 non-glaucomatous eyes of 103 patients who underwent uneventful phacoemulsification and posterior chamber intraocular lens (PCIOL) implantation. Other data which were recorded included best corrected visual acuity, axial length, lens thickness, and severity of lens opacity.

RESULTS

The ACD increased by a mean (SD) of 1.10 (0.44) mm (p<0.00001) and this increase was significantly and inversely related to preoperative ACD (r(2) = 68%; p<0.01). IOP dropped by a mean of 2.55 (1.78) mm Hg following cataract surgery (p<0.0001), and this reduction was significantly and positively related to preoperative IOP (r(2) = 56%; p<0.01), and significantly and inversely related to preoperative ACD (r(2) = 21%; p<0.01). A novel ratio, the pressure to depth (PD) ratio (preoperative IOP/preoperative ACD), was found to be significantly and positively related to the surgically induced reduction in IOP (r(2) = 73%; p<0.01), and IOP was reduced by > or =4 mm Hg in all patients with a PD ratio >7.

CONCLUSION

The reduction in IOP following cataract surgery was found to be positively related to preoperative IOP, and inversely related to preoperative ACD. Furthermore, these results indicate that a novel index, the PD ratio, is strongly predictive for IOP reduction following cataract extraction, and may prove useful in surgical decision making.

Ocular biomechanics and biotransport

The eye transduces light, and we usually do not think of it as a biomechanical structure. Yet it is actually a pressurized, thick-walled shell that has an internal and external musculature, a remarkably complex internal vascular system, dedicated fluid production and drainage tissues, and a variety of specialized fluid and solute transport systems. Biomechanics is particularly involved in accommodation (focusing near and far), as well as in common disorders such as glaucoma, macular degeneration, myopia, and presbyopia. In this review, we give a (necessarily brief) overview of many of the interesting biomechanical aspects of the eye, concluding with a list of open problems.

The Ahmed Glaucoma Valve in Refractory Glaucoma: experiences in Indian Eyes

PURPOSE

To evaluate the efficacy of the Ahmed Glaucoma Valve implant in refractory glaucomas in Indian eyes.

MATERIALS AND METHODS

A retrospective review was conducted on the charts of 122 eyes of 122 patients with refractory glaucoma treated with Ahmed Glaucoma Valve implant placement at Guru Nanak Eye Centre, New Delhi between January 1996 and December 1999. The main outcome measure was success at the last follow-up. Success was defined as an intraocular pressure (IOP) of 22 mmHg or less and 5 mmHg or more and at least a 30% reduction in IOP without visually devastating complications or additional glaucoma surgery.

RESULTS

The mean postoperative IOP (17.29+/-3.79 mmHg) was significantly (P<0.001) lower than the mean preoperative IOP (31.47+/-7.86 mmHg) at last follow up (mean 12.51+/-8.37 months; range 3-24 months). The cumulative probability of success by Kaplan-Meier analysis was 85.95% at 12 months and 82.83% at 24 months. The mean number of postoperative antiglaucoma medications (0.75+/-0.80) was also significantly lower (P<0.001) than the mean preoperative number of antiglaucoma medications (2.83+0.72). The most common complication was corneal-tube contact, which occurred in five (4.10%) eyes. Retinal detachment occurred postoperatively in one eye with the clinical diagnosis of neovascular glaucoma secondary to Eale's disease. Two patients had tube extrusion requiring repositioning and reinforcement with scleral patch graft.

CONCLUSIONS

Ahmed Glaucoma Valve implantation is an effective and relatively safe therapy for the treatment of refractory glaucoma in Indians.