A real mixture of updates in this review. Very common issues such as when to be concerned about choroidal naevi, updates on the management of angle closure glaucoma, managing patients who are interested in alternative therapies, and more.
The nature of the beast: Vitreomacular traction
A study of the natural history of vitreomacular traction syndrome by OCT
Errera MH, Liyanage SE, Petrou P, Keane PA, Moya R, Ezra E, Charteris DG, Wickham L AAO 2017: 125: 701-707
This retrospective clinical case series examined the rates of spontaneous resolution, progression to full-thickness macular hole, and surgical intervention of vitreomacular traction syndrome (VMTS) in the absence of other ocular comorbidities in both asymptomatic and symptomatic patients.
Overall, the mean age was 72 years with a gender distribution of 70% female and 30% male. Focal adhesions were present in 87%. A premacular membrane with macular pucker (PMM) was present in 20%.
VMTS persisted in 60%, resolved in 20% of patients, 12% developed a full thickness macular hole and 8% elected to have surgery for worsening symptoms. On average the timing of resolution or progression occurred after 12 months.
Not surprisingly, the two categories that showed a significant improvement in vision were those with spontaneous resolution or who had surgery for symptoms of VMTS. However those patients that developed a full-thickness macular hole resulted in reduced vision.
Asymptomatic presentation of VMTS was found to not be a predetermining factor for resolution or progression. However the study found a threshold visual acuity of 0.3 logMAR units, whereby those patients with 0.3 logMAR or better showed higher rates of resolution and lower rates of progression.
Another “threshold” discovered was a baseline foveal thickness of 400µm, whereby those thinner than 400µm had a higher rate of resolution and a lower rate of progression.
PMM was associated with broad VMTS, which is supporting evidence of a previously postulated theory that the extent of vitreous attachment could influence regression of vitreofoveal traction. This study also found that those without PMM have a higher rate of resolution and a lower rate of progression, whereas those with PMM had a higher risk of requiring surgery for symptoms.
One of the reasons I routinely perform OCT before cataract surgery is to see if there is VMT. You can’t see it clinically and it is critical to know it is present to avoid disappointed patients. In most cases cataract surgery is still undertaken, with informed consent. There is no evidence that progression or resolution is altered by surgery and the outcome of macular surgery, should it be subsequently needed, is unchanged.
Spot the difference
Choroidal nevi in the Singapore Epidemiology of Eye Disease Study
Ng SR, Zhao W, Mitchell P, Wang JJ, Foo HXV, Neelam K, Cheng CY, Wong TY, Cheung N Ophthalmology 2018:125:784-785
This study examined the possible ethnic and gender differences in prevalence, clinical features and risk factors of choroidal nevi in three major Asian ethnic populations (Chinese, Malay and Indians) living in Singapore.
The overall prevalence of choroidal nevi in this study was 2.1% which is lower than the white populations reported in previous studies, ranging 4.1% to 6.5%.
Nevi were more common in men than women across all ethnic groups with the highest prevalence in men with Chinese ethnicity followed by Indian then Malay. Sex hormones may play a role in the pathogenesis of melancytic tumours as androgen receptors, but not oestrogen or progesterone receptors, have been found in abundance in conjunctival nevi. Also, males with uveal melanoma may have worse prognosis and higher rates of metastasis compared with females.
A lower prevalence or choroidal nevi was associated with increasing grade of nuclear cataract density.
There was no significant difference in the clinical characteristics across the 3 ethnic groups.
The risk factors’ analysis agreed with previous findings that elevated body mass index (BMI) is an associated risk factor for women but not in men and there are no associated systemic factors.
I’m surprised the incidence of naevi was so low in this study and at the quoted incidence for white patients. Indeed, the figure I learned was that 15% of New Zealanders have at least one choroidal naevus. Over the years I’ve had to learn to document naevi, as I often get letters from concerned optometrists (often when they buy retinal cameras) asking if one has been seen before. The critical thing however is not to see naevi but to diagnose small choroidal melanomas. Here I find the acronym ‘To Find Small Ocular Melanomas’ (TFSOM) so helpful. Features more likely to indicate the lesion you are looking at is a melanoma rather than a naevus include: T = Thickness greater than 2 mm, F = subretinal Fluid, S = Symptoms, O = Orange pigment and M = Margin touching optic disc.
Out with the old, in with the new: Is that always best practice?
Changing patterns in treatment of angle closure glaucoma
Napier ML, Azuara-Blanco A Curr Opin Ophthalmol 2018: 29:130-134
Primary Angle Closure (PAC) is a leading cause of blindness with increasing rates as our population grows and ages. The American Academy of Ophthalmology recommends bilateral gonioscopy be performed on all patients with glaucoma, glaucoma suspects and those with elevated IOP upon presentation.
Anterior imaging is not a substitute for gonioscopy. However it has allowed the pathogenesis of angle closure to be better understood. Angle imaging also allows detailed analysis of the angle following treatments including Laser Peripheral Iridotomies (LPI), Argon Laser Peripheral Iridoplasty (ALPI) and Clear Lens Extraction (CLE).
Traditionally, LPI in PAC suspects has been shown to be a well-tolerated intervention, however the benefits (other than in fellow eyes) are uncertain. Examination of the anterior chamber depth following LPI have shown only a temporary widening effect.
Laser therapy is also not that effective in lowering IOP. Trials evaluating ALPI have failed to show a significant long-term IOP lowering effect. Prostaglandin medications are more effective.
It is not surprising, considering the lens plays a significant role in the pathogenesis of PAC, that CLE gives better clinical and quality of life outcomes than LPI in patients with early or moderate primary angle closure glaucoma and primary angle closure with IOP greater than 30mmHg.
There are a couple of key issues here. The first is that anterior segment imaging is no substitute for slit lamp examination and gonioscopy. In my practice I only use it as an education tool. Keep doing gonioscopy! You can’t quantify the risk of angle closure (or even, for that matter diagnose POAG) until the angle has been viewed. Gonioscopy shows you so much more than a cross-section which cannot detect and assess pigment, vessels, anterior synechiae etc. Second, I think we should still do LPIs. The risks are very low and any reduction in risk is worthwhile. It is very important that patients understand that risk reduction rather than risk elimination is the goal. Third, patient education is critical. Keep reminding them of the symptoms of angle closure and to present early. Finally, patients with narrow angles have a 25% risk of slow pressure rise without angle closure. They need to be watched carefully, ideally at least once a year.
Going green: Is there a role for alternative medicines in glaucoma treatment?
Ginkgo biloba and its potential role in glaucoma
Kang JM, Lin S A Curr Opin Ophthalmol 2018: 29:116-120
This literature review looks at research that has studied whether the complementary or alternate medicine gingko biloba extract (GBE) has a potential role in the treatment of glaucoma. GBE has an antioxidant effect, increases ocular blood flow and may provide a neuro-protective effect on the retinal ganglion cells. However, there is inconclusive evidence that GBE improves clinical outcomes such as visual field performance in glaucoma patients.
Many patients take alternative therapies and it is very important we specifically ask when taking a history. Generally there seems little, if any, benefit in glaucoma. Nevertheless one of my glaucoma mentors tells patients that if you are going to take any herbal remedies for your glaucoma, to take Ginko as the there is some evidence it may help. Seems pretty sage.
Blowouts: What’s new?
Orbital “blowout” fractures: time for a new paradigm (editorial)
Kersten RC, Vagefi MR, Bartley GB, Ophthalmology 2018: 125(6):796-798
Conservatively treated orbital blowout fractures spontaneous radiologic improvement
Young SM, Kim Y-D, Kim SW, Byeol H, Lang SS, Cho K, Woo KI Ophthalmology 2018: 125(6):938-944
Each article highlights the evidence that orbital fractures can managed more conservatively and surgical intervention can be delayed longer than 2 weeks, which has been the traditional “window of opportunity”. They emphasise the notable exceptions of white-eyed blowout fractures (usually children) and cases with marked muscle entrapment causing restriction of vertical movement.
The editorial proposes dividing patients into 2 groups – (1) the notable exceptions (above) which do require surgery as soon as practicable and (2) all others. Group 2 comprise the vast majority of blowout fractures. Studies have shown that observation longer than 5-6 months allows time for spontaneous resolution of diplopia and/or development of cosmetically significant enophthalmos (uncommon). Patients can be assured that delayed surgery does not increase the risk of post-operative complications.
The prospective study examined the radiologic findings of 44 blowout fractures treated conservatively. They observed over an average 6 month period, that the majority of patients showed radiologic improvement including smoothening of bony contour (88.6%), joining of bony edges (90.9%), reduction in orbital content herniation (65.9%), features of neobone formation (93.2%), and reduction in both orbital (91.4%) and fracture (94.3%) volumes. Therefore concluding that spontaneous improvement does occur in orbital fractures and surgery can be delayed for many patients, except those discussed above.
Interestingly, the radiologic imaging also indicated an age correlation, whereby there was a greater potential for spontaneous radiologic healing in younger patients.
I appreciate that most optometrists don’t encounter patients with orbital trauma on a regular basis. Nevertheless the data is clear and supports the much more conservative approach adopted by ophthalmologists compared to maxillofacial surgeons. There is a bit of turf warfare in this area at times and I have had some very “robust discussions” over the years with Max Fac colleagues.