Neuro-ophthalmic features of patients with spontaneous cerebrospinal fluid leaks

Timothy Do, Jui-Kai Wang, Toby Steele, E. Bradley Strong, Kiarash Shahlaie, Yin Allison Liu

Medical hypothesis discovery and innovation in ophthalmology, Vol. 12 No. 3 (2023), 31 December 2023 , Page 106-114

Background: Increased intracranial pressure is a potential cause of spontaneous cerebrospinal fluid (sCSF) leak. Associated neuro-ophthalmic features have not been well studied, particularly relationships with idiopathic intracranial hypertension (IIH). We hypothesized that neuro-ophthalmic features routinely used in evaluations for IIH can be useful in the investigation of a causal relationship between IIH and sCSF leak. We reviewed the neuro-ophthalmic examination and office-based ophthalmic imaging data of all consecutive patients with sCSF leaks and at least one repair to investigate the clinical and neuro-ophthalmic features of increased intracranial pressure.
Methods: We conducted a retrospective longitudinal study at a single institution by querying the electronic medical record system for CSF leak Current Procedural Terminology (CPT) codes (G96.00 and G96.01) from June 1, 2019, to July 31, 2022. For patients with a confirmed diagnosis of sCSF leak, demographic information, eye examination results, and ophthalmic imaging details for both eyes were collected.
Results: A total of 189 patients with CSF leaks were identified through CPT coding; 159 had iatrogenic or traumatic CSF leaks, and 30 individuals (3 male, 27 female) had confirmed sCSF leaks. The mean age of patients with sCSF leaks was 46 years (range: 29 – 81), with a mean body mass index of 35.2 kg/m2 (range: 18.2 – 54.1). Only 11 of 30 underwent eye examinations (8 before surgical repair and 10 after). The mean pre-repair and post-repair best-corrected visual acuity were 20/30 (range: 20/20 – 20/55) and 20/25 (range: 20/20 – 20/40), respectively (P = 0.188). The mean retinal nerve fiber layer thickness was 99 mm (range: 96 – 104) pre-repair and 97 mm (range: 84 – 103) post-repair (P = 0.195). The mean ganglion cell complex thickness was 84 mm (range: 72 – 94) pre-repair and 82 mm (range: 71 – 94) post-repair (P = 0.500). Humphrey visual field average mean deviation was -5.1 (range: -12.4 – -1.8) pre-repair and -1.0 (range: -10.1 – 2.1) post-repair (P = 0.063).
Conclusions: Serial neuro-ophthalmic examinations are recommended for patients with sCSF leaks to screen for signs of current or prior increased intracranial pressure. Larger studies are required to clarify the longitudinal changes in neuro-ophthalmic features, to investigate the incidence of IIH in cases of sCSF leak development or recurrence after surgical repair, and to explore potential causal relationships to guide post-repair management and prevent recurrent leaks. A multicenter consortium is also suggested to develop a standard clinical protocol for comprehensive management of sCSF leaks.

Intraocular lens power calculation formulas: a scientometric analysis

Taher Alshammari, Alaa Tarazi, Tasneem Aloqaili, Mohammed Aloqaily, Saif Aldeen AlRyalat

Medical hypothesis discovery and innovation in ophthalmology, Vol. 12 No. 3 (2023), 31 December 2023 , Page 115-126

Background: The most accurate method of intraocular lens (IOL) power calculation in cataract surgery has not been determined, and further studies are needed to reach a consensus. The aim of this study was to assess publications related to IOL power calculation formulas, mapping their yearly trends, most productive authors, top publishing countries and institutions, and areas of specialization for IOL power formulas.
Methods: We conducted a comprehensive analysis of research articles published on the topic of IOL power calculation formulas. Using PubMed, we employed appropriate search terms and filtered the results for the period of January 1, 1946, to June 28, 2023. Data were analyzed using CiteSpace, VOSviewer, and Microsoft Excel programs. The visual representations of the collected data through the use of figures was provided to demonstrate the aspects of IOL power calculation research.
Results: We retrieved 5475 documents in the initial search. Analysis of these documents revealed an increase in the number of publications, from one publication in 1946 to 201 publications in 2023. The top three countries contributing to these publications were the United States, China, and Japan, collectively accounting for over 27% of the total articles. However, the two institutions with the highest contributions were located in the United Kingdom and Hungary, neither of which was among the top 10 countries in overall contributions. Overall 15326 authors contributed to publications pertaining to IOL power calculation formulas. Among these authors, the most prolific contributors included Achim Langenbucher from Saarland University (Germany), Giacomo Savini from G.B. Bietti Foundation I.R.C.C.S. (Italy), and Kenneth J Hoffer from the University of California (United States). Saarland University emerged as the most productive institution, contributing equally to two distinct departments: the Dr. Rolf M. Schwiete Center for Limbal Stem Cell Research and Congenital Aniridia, as well as the Department of Experimental Ophthalmology. The School of Physical Science at the Open University in the United Kingdom engaged in partnership with various institutions including Eye & Laser Clinic Castrop Rauxel in Germany and Johannes Kepler University Linz in Austria. Among the top 10 keywords found in the publications were “cataract”, “cataract surgery”, and “intraocular lens”.
Conclusions: This study represents the first scientometric analysis of publications related to IOL power calculation formulas. The study offers valuable insights into the geographic distribution, contributing authors, and emphasis of research on the IOL power calculation formulas. Further cooperation is essential to pinpoint the most suitable formula and to address gaps in our current understanding.

Impact of flight and equivalent short-term high-altitude exposure on ocular structures and function

Styliani Totou, Efthymios Karmiris, Menelaos Kanakis, Panos Gartaganis, Petros Petrou, Christos Kalogeropoulos, Vassilios Kozobolis, Panagiotis Stavrakas

Medical hypothesis discovery and innovation in ophthalmology, Vol. 12 No. 3 (2023), 31 December 2023 , Page 127-141

Background: Exposure to high-altitude conditions during flight or similar activities affects many aspects of visual function, which is critical not only for flight safety but for any altitude-related activity. We aimed to summarize the available literature pertaining to ocular changes during flight or equivalent short-term high-altitude exposure (e.g., hypobaric chamber, effortless ascent lasting less than or equal to 24 h) and to highlight future research priorities.
Methods: Using the PubMed/MEDLINE and Web of Science/ISI Web of Knowledge databases with structured search syntax, we conducted a systematic review of the literature spanning a 40-year period (January 1, 1983, to October 10, 2023). Articles pertaining to ocular changes during flight or flight-equivalent exposure to altitude were retrieved. The reference lists of retrieved studies were also searched, and citations of these references were included in the results.
Results: Of 875 relevant PubMed and ISI publications, 122 qualified for inclusion and 20 more were retrieved from the reference lists of initially selected records, for a total of 142 articles. Reported anterior segment changes included deterioration in tear film stability and increased dry eye incidence, increased corneal thickness, discomfort and bubble formation in contact lens users, refraction changes in individuals with prior refractive surgery, decreased intraocular pressure, and alterations in pupillary reaction, contrast sensitivity, and visual fields. Photoreceptor–visual pathway changes included alterations in both photoreceptors and neuro-transduction, as evidenced in dark adaptation, macular recovery time, reduction in visual field sensitivity, and optic neuritis (likely an element of decompression sickness). Retinochoroidal changes included increases in retinal vessel caliber, retinal blood flow, and choroidal thickness; central serous chorioretinopathy; and retinal vascular events (non-arteritic ischemic optic neuropathy, high-altitude retinopathy, and retinal vein occlusion).
Conclusions: The effect of short-term high-altitude exposure on the eye is, in itself, a difficult area to study. Although serious impairment of visual acuity appears to be rare, ocular changes, including tear film stability, contact lens wear, central corneal thickness, intraocular pressure, contrast sensitivity, stability of refractive surgeries, retinal vessels, visual fields, and macula recovery time, should be considered in civilian aviators. Our report provides guidance to climbers and lowlanders traveling to altitude if they have pre-existing ocular conditions or if they experience visual symptoms while at altitude. However, key outcomes have been contradictory and comprehensive studies are scarce, especially those pertaining to the choroid and retina. Such studies could not only deepen our understanding of high-altitude ocular pathophysiology, but could also offer valuable information and treatment possibilities for a constellation of other vision-threatening diseases.

Corneal asphericity and its related factors

Abdulaziz Al-Somali , Hussam Muhammad Abouollo, Mohanna Al-Jindan, Ahmed Alothman, Hatlan Alhataln

Medical hypothesis discovery and innovation in ophthalmology, Vol. 12 No. 3 (2023), 31 December 2023 , Page 142-149

Background: Proper correction of spherical aberration using intraocular lenses requires precise selection of the sphericity of intraocular lens surfaces based on individual biometric data and corneal asphericity coefficient (Q value). This study aimed to determine and analyze the corneal Q value and its related factors among Saudi participants.
Methods: In this cross-sectional study, normal right eyes of healthy Saudi participants aged 17 – 58 years who visited Al-Kahhal Medical Complex, Dammam, Saudi Arabia, were included. The Pentacam rotating Scheimpflug camera was used to determine the average Q value at 6-mm diameter. Q values were obtained from each quadrant (superior, nasal, inferior, and temporal) and two meridians (horizontal and vertical). Mean Q values of the anterior and posterior corneal surfaces were also obtained. Other factors including age, sex, refractive error, and central corneal radius were documented.
Results: Five hundred right eyes from 500 participants were included. The mean (standard deviation [SD]) (range) age was 27.2 (7.1) (18 – 58) years. The mean (SD) (range) Q value of 500 eyes was - 0.24 (0.10) (- 0.71 to + 0.09) anteriorly and - 0.16 (0.14) (- 0.70 to + 0.23) posteriorly, being significantly more prolate anteriorly (P < 0.05). The corneas were significantly more prolate in the nasal than in the temporal quadrant, in the superior than in the inferior quadrant, and in the horizontal than in the vertical meridian (all P < 0.05). There were statistically significant differences in anterior, nasal, temporal, inferior, horizontal, and vertical Q values among age groups (all P < 0.05) but not in the superior or posterior Q values (both P > 0.05). The corneas became less prolate with increasing age (P < 0.05). However, Q values were comparable between the sexes (all P > 0.05). There was no significant correlation between anterior (r = + 0.08; P = 0.095) or posterior (r = - 0.08; P = 0.092) Q value and spherical equivalent, but a significant trend was detected toward more prolate shape with increasing myopia in the temporal and inferior quadrants (r = + 0.19; P < 0.001, r = + 0.10; P = 0.022, respectively). There was a significant negligible correlation between the posterior Q value and central corneal radius (r = - 0.18; P < 0.001) but no significant correlation between the anterior Q value and central corneal radius (r = + 0.02; P = 0.673).
Conclusions: Most corneas in this Saudi population were prolate in contour. Anterior corneal asphericity was positively correlated with age and was not significantly related to sex, refractive error, or central corneal radius. Further studies are needed to verify our preliminary findings.

Intravitreal injection of methotrexate in persistent diabetic macular edema: a 6-month study

Nayyereh Razzaghpour, Amin Najafi, Mohammad Rasoul Sabouri, Negin Ashoori, Kourosh Shahraki

Medical hypothesis discovery and innovation in ophthalmology, Vol. 12 No. 3 (2023), 31 December 2023 , Page 150-156

Background: Diabetic macular edema (DME) affects approximately 10% of patients with diabetes mellitus. This condition can cause blurred or distorted vision, which significantly affects the quality of life of these patients. We evaluated the therapeutic effects of intravitreal methotrexate (MTX) injections on persistent DME.
Methods: This prospective interventional case series included patients with confirmed persistent DME that was unresponsive to previous standard treatments. The patients underwent comprehensive eye examinations and macular imaging with optical coherence tomography (OCT). A single intravitreal MTX injection (400 µg MTX in 0.16 mL solution) was administered, followed by patient assessments at 1, 3, and 6 months after injection. Best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), macular thickness (MT), and central subfield thickness (CST) were measured at baseline and post-injection to evaluate treatment efficacy.
Results: We included 33 eyes of 30 patients with a mean (standard deviation [SD], range) age of 62.7 (8.3, 44 to 77) years, of whom 17 (56.7%) were men and 13 (43.3%) were women. All participants had type 2 diabetes mellitus, with a mean (SD, range) duration of 17.0 (6.8, 10 to 31) years. Most participants (n = 27 eyes, 81.8%) had non-proliferative diabetic retinopathy, and six eyes (18.2%) had regressed proliferative diabetic retinopathy. Four eyes (12.1%) had undergone prior macular laser photocoagulation. The mean (SD) number of prior intravitreal bevacizumab injections was 3.4 (0.8), and 29 eyes (87.8%) had received one intravitreal triamcinolone injection. During the study period, a statistically significant difference was observed in CST (P < 0.05); however, no statistically significant differences were observed in BCDVA, MT, or IOP (P > 0.05). Pairwise comparison revealed a significant decrease in CST at 6 months post-injection compared to the baseline value (P < 0.05). During the investigation period, no side effects of MTX, such as macular edema, retinal tears, vitreous hemorrhage, endophthalmitis, or vision loss, were observed.
Conclusions: A single intravitreal MTX injection significantly reduced CST in patients with persistent DME, without relevant safety concerns. However, no significant improvement in functional outcomes was observed. Therefore, there is no strong evidence to recommend its use as a treatment for pDME. Further studies, preferably randomized clinical trials with long-term follow-ups, are warranted to assess the long-term efficacy, safety, and potential benefits of intravitreal MTX for the treatment of persistent DME.