February 04, 2016
3 min read
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Disease advances despite treatment in half of patients with low-pressure glaucoma

Glaucoma progression correlated most strongly with a thin central cornea and disc hemorrhage.

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Disease progression was seen after at least 8 years in about half of patients treated for low-pressure glaucoma, a study found.

The study authors underlined the importance of identifying and following patients with low-pressure glaucoma who are at risk for disease progression and may need aggressive treatment to preserve visual function.

“The real point is that it is unquestionable that some patients with pressures that are low and have progressive, worsening glaucoma can be stabilized,” OSN Glaucoma Board Member George L. Spaeth, MD, told Ocular Surgery News. “The major finding is that patients with progressive glaucoma, even when they have low pressures, can be stabilized.”

The study was published in the European Journal of Ophthalmology.

Long-term follow-up

Spaeth said he and his colleagues set out to answer the question: “Do some patients with glaucoma that has been proven to be progressing have a change in their rate of progression following a pressure-lowering intervention so that they show little or no further progression of damage over a period of greater than 30 years? That was, to me, a concept that is enormously important, which is that if you get the pressure low enough, even in some patients with average pressures, they don’t get worse.”

The researchers wanted to study the records of four patients Spaeth treated in the 1960s, three of whom appeared to have progressive damage despite IOP being in the average range.

“All have been followed with fields and photos since then, and none showed any worsening of their fields, and two showed lasting improvement in both their discs and their fields. This seemed to be totally contrary to what was believed to happen in glaucoma, so I wished to determine if this was a rarity — I knew it was a reality — or more common than a rarity, and how could their lack of worsening be explained?” Spaeth said.

However, most of the patients’ charts were incompletely transferred or not transferred from paper to electronic medical records.

“So, the study question that I wanted to answer could not be answered. But we did have around a 10-year follow on many patients, so I thought it would be worth looking at those, as there are few studies looking at patients for more than a few years,” Spaeth said.

Patients and methods

The retrospective study, conducted at the Wills Eye Hospital Glaucoma Research Center, included 49 eyes of 49 patients who were treated for low-pressure glaucoma for at least 8 years at the Glaucoma Service of Wills Eye between 2000 and 2013.

Mean patient age at baseline examination was 60.7 years.

Investigators assessed systemic disease history, family history of glaucoma, best corrected visual acuity, refractive error, treatments, central corneal thickness, IOP, IOP change after pupil dilation, optic disc evaluation, visual field mean deviation, visual field grading and time to progression.

Progression was defined as worsening optic disc and visual field deterioration.

Mean follow-up was 9.3 years. Mean time to glaucoma progression was 765 days.

At baseline, the progressive glaucoma group and stable glaucoma group had similar visual acuity, IOP and cup-to-disc ratio.

Results

Glaucoma progressed in 25 eyes and remained stable in 24 eyes. Median age at diagnosis was 58 years in the progressive glaucoma group and 63 years in the stable group.

Glaucoma progression tended to correlate with thinner central corneal thickness and disc hemorrhage.

Visual fields were –14.3 dB in the progressive group and –7.6 dB in the stable group at final follow-up; the difference was statistically significant (P = .0003).

Estimated annual change in visual field status was –0.57 dB in the progressive glaucoma group and –0.10 dB in the stable glaucoma group (P < .0001).

Peak IOP was 17.6 mm Hg in the progressive glaucoma group and 15.8 mm Hg in the stable group; the between-group difference was statistically significant (P = .043).

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Final IOP was 12.5 mm Hg in the progressive group and 11 mm Hg in the stable group.

Both groups had statistically similar IOP change after pupil dilation, final IOP and change in IOP from baseline.

Cup-to-disc ratios were 0.74 in the stable glaucoma group and 0.84 in the progressive group at final follow-up; the between-group difference was statistically significant (P = .0009).

The change in cup-to-disc ratio was 0.03 in the stable group and 0.15 in the progressive group (P < .0001).

Average number of medications was 2.1 in the progressive group and 1.9 in the stable group.

Additionally, 48% of patients with progressive glaucoma and 16.7% of patients with stable glaucoma required surgery and laser treatment; the between-group difference was not statistically significant. – by Matt Hasson

Disclosure: Spaeth reports no relevant financial disclosures.