March 15, 2023

The most important ophthalmology research updates, delivered directly to you.
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In this week's issue

  • The cost of complex cataract surgeries are not adequately reflected in extra medicare reimbursements.
  • A clinic run by technicians and overseen by ophthalmologists in Michigan showed positive results for screening low-income patients, though costs were high to operate.
  • Metabolomics profiling of mouse ocular tissues reveal sexual dimorphisms in fed vs. fasted states.

Consortium of Student-Led Eye Clinics (CSLEC)

A message from the CSLEC:
To all members of student-led eye clinics and vision screening programs, we would love to have you join us to unite efforts to increase access to vision care for vulnerable populations! The Consortium of Student-Led Eye Clinics (CSLEC) was founded in 2021 with the Journal of Student-Run Clinics as part of a larger initiative to promote inter-clinic collaboration in specialty care. Please visit our website for more information on how to get involved and join our growing community of 20+ vision screening programs.

Economic comparison of simple and complex cataract surgery

JAMA Ophthalmology

Viewing cataract economics through a clear lens. Cataract surgery is one of the most common surgeries performed worldwide. Although cataract surgery is typically efficient in terms of cost and time, a number of preoperative and intraoperative complications may increase the technical difficulty, required resources, and duration of surgery. Ophthalmologists are reimbursed more for complicated cataract surgery than for uncomplicated cases. However, it is unclear whether this difference is adequate to compensate for the increased expenditure. In a retrospective analysis of 13,904 simple and 2,188 complex cataract surgeries, investigators compared the time-based day-of-surgery costs and reimbursement for each. Time-based day-of-surgery costs were $1486.24 for simple cataract surgery and $2205.83 for complex cataract surgery. In addition, supplies and materials cost $158.26 more for complex cataract surgery. Incremental Medicare reimbursement was only $231.01 higher for complex cataract surgeries. Compared with simple cataract surgery, these figures show that complex cataract surgeries in the study time period had a negative earnings difference of $646.84. This study indicates a failure to adequately reimburse for the time and resources necessary for complex cataract surgery, potentially warranting increased reimbursement for cataract surgery in the future.

Is teleophthalmology the key to increasing access to ophthalmic care?

American Journal of Ophthalmology

The doctor may NOT see you now! Over the last few years, teleophthalmology has gained strong support as an approach to help increase patient access to ophthalmic care. This cohort study followed 1,171 patients from a free clinic and a federally qualified health center in Michigan as they underwent ophthalmic testing and imaging by ophthalmic technicians in these clinics. The patient data was interpreted by remote ophthalmologists and recommendations were shared with patients at future follow-up appointments. Based on the screening by technicians, 71% of patients received low-cost glasses and 41% of patients were referred for ophthalmology follow-up. Although this was a high-rate of follow-up for screening, the clinic successfully alleviated unnecessary costs for a majority of patients. At the same time, the cost of the clinic was high ($103,185 for start-up, $248,103 recurrent costs).

Ocular tissue shows sexually dimorphic metabolic profiles in fed vs fasted states


Battle of the sexes! It is well known that sexual dimorphism plays a role in eye health and disease (e.g. males have more M-and L- cone photoreceptors and females are more susceptible to age-related diseases like AMD and cataracts). Many of the ocular diseases with sex-different prevalence can result from disturbances in metabolic processes. While sexually dimorphic metabolic profiles have been characterized in adipose tissue, muscle, and liver, the metabolic profile of ocular tissue has not been thoroughly investigated. This study compared 133 metabolites in eye tissues (lens, retina, RPE/choroid) from mice deprived of food for 18 hours to a cohort fed ad libitum.  Compared to fed males, the retinas of fed female mice showed an increase in metabolites involved in CoA synthesis and NAD(P) metabolism. In the fasted state, the number of sex-specific retinal, RPE/choroid, and lens metabolites decreased and both sexes showed increased metabolites involved with ketone synthesis and fatty acid oxidation. Interestingly, pantothenic acid, a primary CoA precursor, was the only metabolite consistently elevated in all conditions in females relative to males. Finally, female lens tissue had higher glucose and lower antioxidant metabolites than male counterparts, suggesting that the female lens may be more sensitive to oxidative stress. Similar studies evaluating tissue-specific sex-differences are key to identifying factors responsible for sexually dimorphic susceptibility to diseases as well as targets for intervention with food, supplements, and/or medicines.


Management of Pythium keratitis: Combination of antibiotics vs monotherapy


Pythium is a challenging microbe, so prepare for trouble! Pythium Insidosum keratitis is a challenging cause of microbial keratitis prevalent in tropical countries and commonly misdiagnosed as fungal keratitis. Most cases require early surgical intervention and both linezolid and azithromycin are used for management. Recently, treatment with linezolid as monotherapy was found to be successful in an in vivo rabbit model. Based on that, this prospective randomized double-masked trial evaluated the effectiveness of monotherapy vs combination therapy in cases of Pythium keratitis. 20 patients with microbiologically confirmed Pythium keratitis from September 2019 to March 2020 were included and randomized into linezolid monotherapy (group A, 10 patients) or linezolid and azithromycin therapy (group B, 10 patients). At 2 weeks of treatment, 3 patients in group A showed signs of clinical worsening (avg. mean infiltrate size of 5.9 ± 1.2 mm), while in group B, all patients were showing clinical resolution (avg. infiltrate size 4.9 ± 1.78 mm). At 3 months, those in combination therapy were more likely to have an almost or entirely resolved infection (8:2) and less likely to need penetrating keratoplasty (1:7). This study, although limited by a small sample size, demonstrates that a combination of linezolid and azithromycin has superior clinical efficacy than monotherapy with linezolid for the management of Pythium keratitis.

Lens Landmarks

The horizon may be out of sight, but thanks to the HORIZON trial, a brighter future for glaucoma patients is now in sight. Combined glaucoma and cataract surgery has become increasingly common in North America with the introduction of minimally invasive glaucoma surgery devices and techniques. The HORIZON trial compared clinical outcomes of patients following cataract surgery with (n=369) and without a Hydrus Microstent (n=187)

Key Points:
  • At 5 years, the Hydrus Microstent and Cataract Surgery group (HMS) included a higher proportion of eyes with IOP of 18 mmHg or less without medications than the Cataract Surgery Only (CS) group (49.5% vs. 33.8%; P = 0.003)
  • The HMS group had a greater likelihood of IOP reduction of 20% or more without medications than the CS group (54.2% vs. 32.8%; P < 0.001)
  • The number of glaucoma medications was 0.5 ± 0.9 in the HMS group and 0.9 ± 0.9 in the CS group (P < 0.001), and 66% of eyes in the HMS group were medication free compared with 46% in the CS group (P < 0.001)
  • No clinical or statistically significant differences were found in the rate of endothelial cell loss from 3 to 60 months between the HMS and CS alone groups (P = 0.261)
Overall, the HORIZON landmark study demonstrated that use of a Schlemm's canal microstent in addition to traditional cataract surgery was found to be safe and resulted in lowered intraocular pressure and a reduction in medication use. The study also found that the long-term presence of the microstent did not have a negative impact on the corneal endothelium.

Question of the Week

A 25-year-old African-American male is referred by a hematologist to the retina service for evaluation of blurry vision. He reports floaters but denies flashes and ocular pain. He wears glasses but otherwise has no known ocular history. Vision is 20/30 OD and 20/150 OS. Intraocular pressures are 13 mmHg OD and 14 mmHg OS. He has no RAPD. Fluorescein angiography is obtained during workup, and is significant for the following finding:
What is the most likely diagnosis in the patient? 

A. Open angle glaucoma
B. Diabetes
C. Sickle cell disease
D. Hypertension

Keep scrolling for answer or click here

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Quiz Answer: C
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