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A novel instrument for assessing the retinal red reflex for non-ophthalmic health professionals
Jo-Anne M C Pon1, Tui H Bevin, Peter Herbison
1Ophthalmology Section, Medical and Surgical Sciences Department, University of Otago Dunedin School of Medicine, Dunedin, New Zealand.
Background:
The direct ophthalmoscope is the standard instrument for assessing retinal red reflexes when screening for cataract, however, it is expensive and often not available to non-ophthalmic health professionals. The pen torch ophthalmoscope is a new economic alternative for this purpose. This study aimed to determine its accuracy in assessing retinal red reflexes and to compare it to the direct ophthalmoscope. It is anticipated that this instrument will be useful in detecting both congenital and adult type cataracts.
Methods:
Eighteen health professionals evaluated the retinal red reflexes of 68 subjects at the Dunedin Hospital Eye Clinic with both the direct ophthalmoscope and the pen torch ophthalmoscope. Three groups of seven, six and five observers assessed both eyes of 24, 21 and 23 subjects, respectively, resulting in 1,574 examinations.
Results:
Compared to the direct ophthalmoscope, the pen torch ophthalmoscope exhibited lower sensitivity (68 per cent versus 75 per cent), but higher specificity (72 per cent versus 63 per cent) and lower over-referral (false positive) rates by nine per cent. The positive predictive value in respect to identifying for cataract was better for the pen torch ophthalmoscope (71 per cent) than for the direct ophthalmoscope (66 per cent), while the negative predictive value was slightly worse (70 per cent and 73 per cent, respectively). When compared to the direct ophthalmoscope, 15/18 observers felt the pen torch ophthalmoscope was accurate enough, one felt it was just as good and two did not respond.
Conclusions:
This pilot study demonstrates that the pen torch ophthalmoscope is comparable to the direct ophthalmoscope in detecting abnormal retinal red reflexes in adults with cataracts. At six per cent of the cost of a direct ophthalmoscope, it may appeal to non-ophthalmic health professionals in developed and developing countries. It may also increase the frequency of screening for cataract in children and adults. Further development and study of this pen torch ophthalmoscope prototype is warranted.
