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Link found between statins and glaucoma neuroprotection
Investigators call for further research to determine if the cholesterol-lowering drugs might someday play a role in slowing glaucomatous damage.
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Statin drugs could act as a neuroprotective agent for glaucoma suspect patients, preventing progression of optic nerve head parameters, a study found.
Shan C. Lin, MD, and colleagues conducted a retrospective chart review, published in Clinical & Experimental Ophthalmology, that examined the role of statins and aspirin on reducing progression of optic nerve parameters in glaucoma suspects.
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The researchers examined data from 149 eyes of 76 glaucoma suspects who had at least two confocal scanning laser ophthalmoscopy tests. Patients considered glaucoma suspects had a cup-to-disc ratio of more than 0.5, asymmetric cupping with a difference of more than 0.2, irregular cupping, or notching or thinning of the neuroretinal rim, they said. Patients had normal IOP and lacked visual field defects.
Subjects were divided into four groups: those who were taking statins, those who were taking aspirin, those who were taking both statins and aspirin, and a control group that was taking neither. Those who were taking statins must have been taking them for at least 23 months at the study onset.
Dr. Lin and colleagues found that the group of patients on statins (24 eyes of 12 patients) had significant increases in rim volume, retinal nerve fiber layer cross-sectional area, mean global retinal nerve fiber layer thickness and superotemporal, inferotemporal, superonasal and inferonasal retinal nerve fiber layer thickness.
“Statin drugs may be neuroprotective, via blockade of glutamate-mediated cytotoxicity or through their anti-inflammatory effects,” Dr. Lin said in an e-mail interview with Ocular Surgery News. “Aspirin has also shown neuroprotective effects, but its use was not associated with preventing progression in our study.”
The patient group taking both statins and aspirin (23 eyes of 12 patients) had a statistically significant increase in retinal nerve fiber layer cross-sectional area and inferonasal retinal nerve fiber layer thickness, Dr. Lin and colleagues found.
Both the aspirin-only group (26 eyes of 13 patients) and the statin and aspirin group had a trend toward glaucoma protection in the cup and rim areas and mean cup depth, maximum cup depth and different measurements of the retinal nerve fiber layer thickness, the study found. However, those results were not significant compared with the control group, which consisted of 76 eyes of 39 patients.
Statin drugs
Statin drugs are most commonly prescribed to lower cholesterol and help prevent coronary artery disease and stroke, according to Dr. Lin and colleagues. The drugs work as selective inhibitors of HMG-CoA reductase. Statins have also been studied for their impact on reducing inflammation in nerve cells and preventing neuronal cell death after ischemic injury, they said.
Research has found that neuroprotective drugs preventing optic nerve ischemia and inflammation could possibly delay or prevent further glaucoma damage and progression, they said.
However, Dr. Lin cautioned that while the study results look promising for statins, if the drugs were taken for a chronic disease such as glaucoma, patients could be exposed to side effects over an extended period.
He said prospective, controlled studies are needed to determine the exact role that statins play in delaying glaucomatous progression before they become part of adjunctive glaucoma therapy or preventative therapy.
“At this time, I would not recommend the institution of statin use expressly for the prevention of glaucoma in suspect patients,” Dr. Lin said. “These drugs have potential serious systemic side effects, particularly in the liver and muscles. A large, prospective, randomized clinical trial is necessary to conclude that statins are truly effective against glaucoma development.”
The study also found that while patients in the statin-only group appeared to have suspended progression, patients on both statins and aspirin did not have similar results. Dr. Lin and colleagues hypothesized that this could be because patients taking both statins and aspirin were more likely to have more severe dyslipidemia and coronary artery disease, both of which may be significant factors related to glaucoma progression, than patients on statins only.
Another reason could be that the two drugs have different effects on the optic nerve, they said.
Aspirin
The investigators hypothesized that aspirin would also delay glaucoma progression, but they did not find evidence to support this.
Dr. Lin and colleagues said that because aspirin potentially has similar anti-inflammatory abilities as statins and a possible neuroprotective effect by inhibiting glutamatergic excitotoxicity, they suspected aspirin might show the same results.
“It is likely that aspirin may not prevent glaucoma development as we had hypothesized,” Dr. Lin and colleagues said in the study.
Dr. Lin emphasized in the interview that the study had limitations, including the small number of patients and the fact it was a retrospective chart review instead of a prospective study, so aspirin’s effects should not be completely discounted at this point.
For more information:
- Shan C. Lin, MD, is an assistant professor of clinical ophthalmology at UCSF School of Medicine. He can be reached at Box 0730, 10 Koret Way, San Francisco, CA 94143-0730; e-mail: lins@vision.ucsf.edu.
Reference:
- De Castro DK, Punjabi OM, et al. Effect of statin drugs and aspirin on progression in open-angle glaucoma suspects using confocal scanning laser ophthalmoscopy. Clin Experiment Ophthalmol. 2007;35:506-513.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.