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July 6, 2022


The most important ophthalmology research updates, delivered directly to you.
 

In this week's issue

  • Among school aged children, increasing outdoor time reduced the risk of myopia onset and myopic shifts over a two-year period.
  • More nAMD patients (>90%) preferred port delivery systems to intravitreal injections, but both techniques achieved good treatment satisfaction scores. 
  • SF6 gas tamponade may help reduce postoperative vitreous hemorrhage after diabetic vitrectomy when compared to using BSS.
  • OCT angiography may be a useful tool for evaluating limbal-conjunctival grafts after pterygium surgery. 

New recommendation for myopia prevention? Fun in the sun!

Ophthalmology

Increased outdoor time reduces risk of myopia onset in children. Half the global population is estimated to be myopic by 2050. Increased time spent outdoors has been shown to reduce the progression of myopia, although the threshold of its protective effect has not been quantified. This study evaluated the dose-response efficacy of increased outdoor time on myopia onset and shift in a two-year, prospective, cluster-randomized, examiner-masked, three-arm trial. 6295 students (ages 6-9) from 24 schools in Shanghai, China were randomly assigned to one of three groups: control group participants maintained their baseline outdoor time, test I added 40 minutes, and test II added 80 minutes. Students were given a wristwatch to objectively monitor daily outdoor time and light intensity. Increased outdoor time reduced the incidence of myopia onset by 16% in test I and 11% in test II compared to the control group. The study model calculated reducing incidence risk by 25-30% requires at least an additional 65-80 minutes of outdoor time per day, with more needed at lower light intensity. The dose-response effect was not observed between the two test groups, however this may be due to limitations such as failure to meet targets for time spent outdoors (particularly in test II) and 10% loss to follow-up per year. Not only does this study affirm the protective effects of outdoor time on myopia is related to duration of exposure and light intensity, but its quantitative model may be used to design strategies for prevention in various geographic settings.  

Patients prefer PDS over intravitreal injections for nAMD

JAMA Ophthalmology

Don’t forget to ask the patient what they prefer! Port delivery system (PDS) is a surgically implanted reservoir of ranibizumab and an alternative to repeat intravitreal injections (IVI) for nAMD. This phase 3, randomized, multicenter clinical trial investigated whether patients with nAMD prefer PDS with exchanges every 24 weeks or IVI every 4 weeks using the Macular Disease Treatment Satisfaction Questionnaire (MDTSQ) and PDS Patient Preference Questionnaire (PPPQ). The MDTSQ measured whether patients in both treatment arms were satisfied with their treatment outcome and the PPPQ measured the proportion of patients in the PDS treatment arm that preferred PDS over IVI . At 40 weeks, the PPPQ questionnaire revealed that most patients with previous IVI preferred PDS treatment (218/234, 93.2%) with most (172/234) having a very strong preference for PDS over IVI. Patients with fellow eye concurrent IVI also preferred PDS (72/78, 93.2%). At 40 weeks, there was minimal differences in MDTSQ treatment satisfaction scores between the PDS and IVI groups (mean, 68.0; 95% CI, 67.4-68.6; n = 237 and mean, 66.1; 95%CI, 64.9-67.3; n = 159, respectively; difference, 1.9; 95%CI, 0. 7-3.1).  Overall, these results indicate that PDS was the treatment preference of most nAMD patients and both PDS and IVI achieve great treatment satisfaction scores.

SF6 vs BSS to avoid post-vitrectomy vitreous hemorrhage

American Journal of Ophthalmology

Rock beats paper - paper beats scissors - but does SF6 beat BSS? Vitreous hemorrhage (VH) is a common complication among patients with proliferative diabetic retinopathy (PDR) after vitrectomy. While some VH may be expected in the early postoperative period, some patients do not experience spontaneous resolution. Because persistent VH can be vision-limiting and may require further surgical intervention, researchers sought to determine potential differences in post-vitrectomy VH based on vitreous substitution. This prospective randomized clinical trial included 144 patients with PDR and non-clearing VH undergoing vitrectomy. Patients were randomly assigned to one of two groups based on vitreous substitution material: sulfur hexafluoride (SF6) gas tamponade or substitution with balanced salt solution (BSS). After a 6-month follow-up period, the incidence of postoperative VH in the group utilizing SF6 was 11.1% compared to 33.3% in the group utilizing BSS (P=0.01), suggesting a trend towards a lower rate of postoperative VH in subjects where an SF6 tamponade was used. While certain limitations restrict the study from claiming statistical significance, the results may be useful in guiding specialist decision-making to aid in the reduction of postoperative VH in patients with PDR.

OCT angiography for limbal-conjunctival graft healing

Eye

Can OCTA be used for monitoring limbal-conjunctival grafts, and not just for the retina? The main treatment for a pterygium (PTG) is surgical removal and limbal-conjunctival autograft (LCA) after excision has shown to decrease PTG recurrence from 24-89% (with sole excision) to 5-15%. However, graft health depends heavily on graft revascularization. This study sought to analyze optical coherence tomography angiography (OCTA), a noninvasive vascular imaging modality, as a method for assessing postoperative angiogenesis and tissue healing in LCAs after PTG excision. This was a prospective study of seven patients undergoing PTG excision with LCA transplantation procedure, who received anterior segment OCTA preoperatively and on postoperative day (POD) 1, 3, 7 and 30. OCTA results showed minimal or no flow signal in all autografts on POD 1 (mean 7.1 ± 3.3%), with regrowth of disorganized blood vessels into the graft on POD3 (8.7 ± 3.6%) to 7 (14.3 ± 4.1%), and revascularization flow signal throughout nearly all grafts on day 30 (21.6 ± 2.2%). Graft edema reduced substantially from the first week (mean 611 ± 120 μm, 695 ± 84 μm, 639 ± 96 μm of POD 1, 3 and 7, respectively) to day 30 (300 ± 108 μm). Revascularization originated from the underlying episcleral vessels rather than graft borders, emphasizing the importance of careful management of the bare sclera during surgery. OCTA imaging is a good modality for monitoring LCA graft health during the early postoperative period, showing that revascularization occurs during POD 3-7, associated with a decrease in edema. Future OCTA studies may reveal the effects on revascularization and PTG recurrence from the various types of PTG treatment, such as fibrin glue, sutures, cauterization, graft preparation, and postoperative management.

Retina

Air vs. SF6 tamponade for uncomplicated retinal detachments with inferior breaks

Retina

If the break is low, to air we go? Intraocular gasses are important tools used in the repair of rhegmatogenous retinal detachment (RRD) due to their ability to provide internal tamponade for retinal breaks before being absorbed into the bloodstream. Tamponade agents such as octafluoropropane (C3F8) and sulfur hexafluoride (SF6) are generally preferred over filtered room air for complex RRDs due to their sustained presence within the eye, however the efficacy of air tamponade in treating RRDs from inferior breaks is still up for debate. In this retrospective study, 116 eyes underwent primary pars plana vitrectomy (PPV) for uncomplicated RRD with causative inferior retinal breaks (between 4 and 8 o'clock positions) using either filtered room air or 20% SF6 gas tamponade. Exclusion criteria included eyes with proliferative vitreoretinopathy, prior vitreoretinal surgery, macular disease, ocular trauma, vitreous hemorrhage, and no posterior vitreous detachment. No significant differences were found in single-surgery anatomical success rates (96.2% vs. 93.8%) or final visual recovery (20/23 vs. 20/21) when comparing air with SF6 gas. In light of some countries banning the use of SF6 gas due to its potent greenhouse gas effects, air tamponade should be considered as an acceptable alternative for repair of uncomplicated RRD with inferior breaks.  

Lens Landmarks

An ounce of eye drops might be worth a pound of prevention. In the 2002 OHTS trial, subjects with ocular hypertension (but not glaucoma) were randomized to observation or to topical treatment to reduce IOP by 20% and to <24 mmHg. Subjects were monitored for the development of glaucoma.

Key Points:
  • At 60 months, 4.4% of subjects in the treatment group and 9.5% in the observation group developed POAG (P < 0.0001).
  • Treatment reduced IOP in ocular hypertensive subjects from a mean of 25 mmHg to a mean of 19 mmHg while maintaining a favorable safety profile.
Overall, the landmark OHTS trial showed that treating ocular hypertension reduced the risk of developing POAG by more than half. Clinicians should consider treatment in ocular hypertensive patients with moderate to high risk of developing glaucoma.

Question of the Week

A 67 year old woman complains of ptosis and diplopia which has progressed over the past year.  Examination of the left eye is unremarkable. Examination of the right eye reveals 4 mm of ptosis as well as limitation of eye movement in all directions. The right eye also has a smaller 4 mm pupil that does not react to light or dilate in darkness and loss of corneal sensation.
What is the most likely diagnosis?

A. Myasthenia Gravis
B. Graves ophthalmopathy
C. Intracavernous meningioma
D. Aneurysm of the PCA
E. Glioma of the right midbrain


 
Keep scrolling for answer or click here
 

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