A year ago, a 45-year-old insulin dependent diabetic Asian patient did not want an eye examination carried out by us because we did not provide free NHS spectacles and we would not entertain her request for strong reading spectacles. She therefore had an eye examination with another optical practice and she was seen by us just for the diabetic screening. She was prescribed spectacles with a reading add of +2.75D (a 45-year-old with such high reading add?).
At this visit the patient was noted to have high intraocular pressures of 24mmHg in the right eye and 27mmHg in the left eye. Her diabetic findings were R0 (no diabetic retinopathy) right and left eye. She was immediately referred to an eye specialist for ocular hypertension.
A year on from this visit she decided to have a full eye examination including diabetic screening. On further questioning about her assessment with an eye specialist she confessed that she was diagnosed as having high pressures but she felt belittled by the consultant who in her words 'Made me cry and kept shouting that I should keep my eyes wide open'. A reassessment appointment was made for three months' time but she did not go back after her experience.
At this visit her spectacle prescription remained unchanged at:
6/12 R. +1.00DS/-0.50DC X 70 VA 6/6 Add +2.75DS N5
6/12 L. +1.00DS/-0.75DC X 105
VA 6/6 Add +2.75DS N5.
Ocular findings
? R0 - no diabetic retinopathy right and left eye
? Intraocular pressures R 21mmHg and L 26mmHg (Perkins 10.30am)
? Corneal thickness R 483 microns and L 478 microns
? True intraocular pressures R 25mmHg and L 30mmHg.
? Both eyes had moderately open angles
? Visual field test revealed no central field defect
? Cup disc ratio was 0.6 in each eye
?e_STnSRetinal nerve fibre analysis with the ocular coherence tomography (OCT) glaucoma assessment test revealed thick nerve fibres in each eye (Figure 1)
? The right eye had 101 microns superior and inferior thickness while the left eye had thicker 108 microns superior and inferior thickness.
Decision taken
The patient was told that her pressures were still a concern and she needed to be seen by an eye specialist to prevent further damage to her nerve fibres and eventually loss of visual field. The left eye pressure was 30mmHg when corneal thickness was taken into account. She was persuaded to see another consultant and with the help of her GP a fresh appointment was made for her to see a new specialist.
It would have been easier not to have bothered with this patient in the first place and retinal images would never have shown ocular hypertension and, remember, the patient's eye examination with the optometrist from whom she purchased her spectacles did not pick out the high pressures.
We as optometrists should always be vigilant with regards to glaucoma and this can be in the form of high pressures or due to nerve fibre damage with normal- or low-tension glaucoma. The patient's attitude with regards to trying to get professional service at a cheap price proved foolhardy in the long run.
Case 2
Could it be glaucoma?
A 75-year-old borderline diabetic was seen for a diabetic retinal examination and she was under annual review by a local eye clinic. She was hypertensive and hyperlipidaemic and her diabetes was diet controlled. Two years ago while watching television she noticed a grey line in front of her left eye. The eye specialist could not find a definite cause for the visual field defect and she was told it could be neurological or vascular.
Ocular findings
? Grade R0 - no diabetic retinopathy
? Optic discs revealed asymmetrical optic disc cupping (Figure 2)
? The left optic disc when observed carefully showed a deep cupping inferiorly and the bayoneting of the inferior vessel is apparent of stereo Volk lens observation. Close inspection of the left optic disc fundus image also reveals the inferior neural retinal rim thinning and an inferior notch while the superior shows a much deeper red colouring
? Intraocular pressures with corneal thickness of 570 microns each eye revealed R 21mmHg and L 20mmHg
? Visual field test revealed no defect in the right eye full 60 degree field - full threshold field testing was done as the specialist told the patient that the defect was probably neurological (Figure 3)
? The left visual field revealed a superior scotoma respecting the horizontal meridian and not respecting the vertical meridian. The field defect was superior nasal and this matches the inferior temporal nerve fibre loss
? OCT retinal nerve fibre analysis revealed a definite loss of nerve fibres in the inferior aspect of the left eye. The superior nerve fibre thickness was 93 microns, while the inferior layer thickness was a measly 69 microns (Figure 4). I have rotated the nerve fibres vertically and now you can see the field defect and the loss of nerve fibres matching exactly
? The right eye had fairly thick nerve fibres at nearer 100 microns both in the superior and inferior RNFL layer
? The OCT cup disc ratio shows that the right eye was roughly 0.5 while the left eye was a deeper 0.8 cup disc ratio
? The ganglion cell complex which measures the thickness of the ganglion cell superiorly and inferiorly at the macula shows that the right eye has thick ganglion cells measuring 86 microns in the superior part and 80 microns inferiorly. The left eye ganglion cell thickness shows that the inferior ganglion cell complex is 40 microns compared to 74 microns in the superior aspect
? The focal volume loss also shows 21 per cent loss in the left eye compared to 4 per cent for the right eye
? The left macular scan revealed a slight epiretinal membrane and definite slight thickening and distortion of the nerve fibres layer.
Decision taken
The patient was reassured that she did not have diabetic retinopathy and that we would undertake nerve fibre analysis in a year's time to assess if there were any loss of nerve fibres. Observation of the optic disc shows a suspect left optic disc especially the inferior part of the disc. The vein as it emerges from the inferior part of the disc is reminiscent of deep glaucoma cupping. The cup/disc ratio that the specialist estimated was 0.4 in the left eye compared to 0.8 estimated by the OCT.
The distribution of the nerve fibres also points to loss of nerve fibres in the left eye on the inferior aspect. The ganglion cell complex also shows definite loss of ganglion cells in the inferior aspect. This inferior loss in the left eye mirrors the superior field loss in the left eye.
There is no defect in the right eye field, so this would discount a neurological cause for the field defect. It is likely to be either retinal or retrobulbar or ischaemic optic neuropathy. Glaucoma is high on the suspicion list, so further field examination and nerve fibre analysis would give a better picture over the next couple of years as to whether this is glaucoma or an anomaly.
The patient was discharged by her specialist into our care with the confidence that she would be thoroughly monitored. ?
? Kirit Patel practises in Radlett, Hertfordshire