Late glaucoma presentation risks sight loss
MedWire News: Study results from a UK eye hospital show that the majority of patients with glaucoma who are on the certification of visual impairment register already had significant visual impairment at diagnosis.
This is despite some patients already being in the care of the National Health Service (NHS) hospital eye service, say the researchers who believe that delays to impairment certification could be due to patients presenting late with glaucoma.
Furthermore, advanced glaucoma patients may have a severe visual field (VF) defect but a reasonable visual acuity, making them ineligible for certification under the sight impaired (S) or severely sight impaired (SSI) criteria.
"Perhaps it is time to revisit the UK Department of Health definitions of SI and SSI," suggest Wendy Franks (Moorfields Eye Hospital, London) and colleagues in the British Journal of Ophthalmology.
The team reviewed the medical records of 100 consecutive glaucoma patients certified as SI or SSI in the UK certification of visual impairment database. Over half (n=57) of these patients presented with bilateral SSI.
However, Franks and colleagues point out that while these patients may have presented at the study institution already having bilateral SSI, that they may have already been seen by other NHS clinicians or institutions in the course of their illness.
This could explain, in part, why the current data shows that a high proportion presented with bilateral visual impairment.
The team remarks that a number of other factors, including low educational and socioeconomic levels, are known to be associated with unawareness of visual problems. In addition, non-White patients - over-represented on the UK visual impairment register - are known to lack general awareness of glaucoma.
"This may suggest that targeted public awareness programmes specific to certain ethnicities may help reduce later presentation of the disease," write the study authors.
Age could also be a factor; patients with bilateral SSI were older than those with less severe disease, at 70.4 years versus 61.2 years, which could indicate that they have a lower expectation of their health.
Finally, the certification process itself may hinder ophthalmologists as it gives little guidance on the distinctions between total and extensive loss of VF.
"Using visual acuity data alone in the definition of 'blindness' severely underestimates the number of persons visually and functionally impaired from glaucoma," the researchers conclude.
By Sarah Guy