PURPOSE: Pediatric optic neuritis (ON) is a rare disease that has not been well characterized. The Pediatric ON Prospective Outcomes Study (PON1) was the first prospective study to our knowledge aiming to evaluate visual acuity (VA) outcomes, including VA, recurrence risk, and final diagnosis 2 years after enrollment. DESIGN: Nonrandomized observational study at 23 pediatric ophthalmology or neuro-ophthalmology clinics in the United States and Canada. PARTICIPANTS: A total of 28 (64%) of 44 children initially enrolled in PON1 (age 3-<16 years) who completed their 2-year study visit. METHODS: Participants were treated at the investigator's discretion. MAIN OUTCOMES MEASURES: Age-normal monocular high-contrast VA (HCVA). Secondary outcomes included low-contrast VA (LCVA), neuroimaging findings, and final diagnoses. RESULTS: A total of 28 participants completed the 2-year outcome with a median enrollment age of 10.3 years (range, 5-15); 46% were female, and 68% had unilateral ON at presentation. Final 2-year diagnoses included isolated ON (n = 11, 39%), myelin oligodendrocyte glycoprotein-associated demyelination (n = 8, 29%), multiple sclerosis (MS) (n = 4,14%), neuromyelitis optica spectrum disease (NMOSD) (n = 3, 11%), and acute disseminated encephalomyelitis (n = 2, 7%). Two participants (7%; 95% confidence interval [CI], 1-24) had subsequent recurrent ON (plus 1 participant who did not complete the 2-year visit); all had MS. Two other participants (7%) had a new episode in their unaffected eye. Mean presenting HCVA was 0.81 logarithm of the minimum angle of resolution (logMAR) (∼20/125), improving to 0.14 logMAR (∼20/25-2) at 6 months, 0.12 logMAR (∼20/25-2) at 1 year, and 0.11 logMAR (20/25-1) at 2 years (95% CI, -0.08 to 0.3 [20/20+1-20/40-1]). Twenty-four participants (79%) had age-normal VA at 2 years (95% CI, 60-90); 21 participants (66%) had 20/20 vision or better. The 6 participants without age-normal VA had 2-year diagnoses of NMOSD (n = 2 participants, 3 eyes), MS (n = 2 participants, 2 eyes), and isolated ON (n = 2 participants, 3 eyes). Mean presenting LCVA was 1.45 logMAR (∼20/500-2), improving to 0.78 logMAR (∼20/125+2) at 6 months, 0.69 logMAR (∼20/100+1) at 1 year, and 0.68 logMAR (∼20/100+2) at 2 years (95% CI, 0.48-0.88 [20/50+1-20/150-1]). CONCLUSIONS: Despite poor VA at presentation, most children had marked improvement in VA by 6 months that was maintained over 2 years. Associated neurologic autoimmune diagnoses were common. Additional episodes of ON occurred in 5 (18%) of the participants (3 relapses and 2 new episodes).

PURPOSE: Over the past two decades, advancements in imaging modalities have significantly evolved the diagnosis and management of retinal diseases. Through these novel platforms, we have developed a deeper understanding of the anatomy of the choroidal vasculature and the choriocapillaris. The recently developed tools such as optical coherence tomography (OCT) and OCT angiography (OCTA) have helped elucidate the pathological mechanisms of several posterior segment diseases. In this review, we have explained the anatomy of the choriocapillaris and its close relationship to the outer retina and retinal pigment epithelium. METHODS: A comprehensive search of medical literature was performed through the Medline/PubMed database using search terms: choriocapillaris, choroid, quantification, biomarkers, diabetic retinopathy, age-related macular degeneration, choroidal blood flow, mean blur rate, flow deficit, optical coherence tomography, optical coherence tomography angiography, fluorescein angiography, indocyanine green angiography, OCTA, Doppler imaging, uveitis, choroiditis, white dot syndrome, tubercular serpiginous-like choroiditis, choroidal granuloma, pachychoroid, toxoplasmosis, central serous chorioretinopathy, multifocal choroiditis, choroidal neovascularization, choroidal thickness, choroidal vascularity index, choroidal vascular density, and choroidal blood supply. The search terms were used either independently or combined with choriocapillaris/choroid. RESULTS: The imaging techniques which are used to qualitatively and quantitatively analyze choriocapillaris are described. The pathological alterations in the choriocapillaris in an array of conditions such as diabetes mellitus, age-related macular degeneration, pachychoroid spectrum of diseases, and inflammatory disorders have been comprehensively reviewed. The future directions in the study of choriocapillaris have also been discussed. CONCLUSION: The development of imaging tools such as OCT and OCTA has dramatically improved the assessment of choriocapillaris in health and disease. The choriocapillaris can be delineated from the stromal choroid using the OCT and quantified by manual or automated methods. However, these techniques have inherent limitations due to the lack of an anatomical distinction between the choriocapillaris and the stromal choroid, which can be overcome with the use of predefined segmentation slabs on OCT and OCTA. These segmentation slabs help in standardizing the choriocapillaris imaging and obtain repeatable measurements in various conditions such as diabetic retinopathy, age-related macular degeneration, pachychoroid spectrum, and ocular inflammations. Additionally, Doppler imaging has also been effectively used to evaluate the choroidal blood flow and quantifying the choriocapillaris and establishing its role in the pathogenesis of various retinochoroidal diseases. As tremendous technological advancements such as wide-field and ultra-wide field imaging take place, there will be a significant improvement in the ease and accuracy of quantifying the choriocapillaris.

BACKGROUND: In eyes with diabetic macular edema, the relative efficacy of administering aflibercept monotherapy as compared with bevacizumab first with a switch to aflibercept if the eye condition does not improve sufficiently (a form of step therapy) is unclear. METHODS: At 54 clinical sites, we randomly assigned eyes in adults who had diabetic macular edema involving the macular center and a visual-acuity letter score of 24 to 69 (on a scale from 0 to 100, with higher scores indicating better visual acuity; Snellen equivalent, 20/320 to 20/50) to receive either 2.0 mg of intravitreous aflibercept or 1.25 mg of intravitreous bevacizumab. The drug was administered at randomization and thereafter according to the prespecified retreatment protocol. Beginning at 12 weeks, eyes in the bevacizumab-first group were switched to aflibercept therapy if protocol-specified criteria were met. The primary outcome was the mean change in visual acuity over the 2-year trial period. Retinal central subfield thickness and visual acuity at 2 years and safety were also assessed. RESULTS: A total of 312 eyes (in 270 adults) underwent randomization; 158 eyes were assigned to receive aflibercept monotherapy and 154 to receive bevacizumab first. Over the 2-year period, 70% of the eyes in the bevacizumab-first group were switched to aflibercept therapy. The mean improvement in visual acuity was 15.0 letters in the aflibercept-monotherapy group and 14.0 letters in the bevacizumab-first group (adjusted difference, 0.8 letters; 95% confidence interval, -0.9 to 2.5; P = 0.37). At 2 years, the mean changes in visual acuity and retinal central subfield thickness were similar in the two groups. Serious adverse events (in 52% of the patients in the aflibercept-monotherapy group and in 36% of those in the bevacizumab-first group) and hospitalizations for adverse events (in 48% and 32%, respectively) were more common in the aflibercept-monotherapy group. CONCLUSIONS: In this trial of treatment of moderate vision loss due to diabetic macular edema involving the center of the macula, we found no evidence of a significant difference in visual outcomes over a 2-year period between aflibercept monotherapy and treatment with bevacizumab first with a switch to aflibercept in the case of suboptimal response. (Funded by the National Institutes of Health; Protocol AC ClinicalTrials.gov number, NCT03321513.).

Visual symptoms are common after concussion in children and adolescents, making it essential for clinicians to understand how to screen, identify, and initiate clinical management of visual symptoms in pediatric patients after this common childhood injury. Although most children and adolescents with visual symptoms after concussion will recover on their own by 4 weeks, for a subset who do not have spontaneous recovery, referral to a specialist with experience in comprehensive concussion management (eg, sports medicine, neurology, neuropsychology, physiatry, ophthalmology, otorhinolaryngology) for additional assessment and treatment may be necessary. A vision-specific history and a thorough visual system examination are warranted, including an assessment of visual acuity, ocular alignment in all positions of gaze, smooth pursuit (visual tracking of a moving object), saccades (visual fixation shifting between stationary targets), vestibulo-ocular reflex (maintaining image focus during movement), near point of convergence (focusing with both eyes at near and accommodation (focusing with one eye at near because any of these functions may be disturbed after concussion. These deficits may contribute to difficulty with returning to both play and the learning setting at school, making the identification of these problems early after injury important for the clinician to provide relevant learning accommodations, such as larger font, preprinted notes, and temporary use of audio books. Early identification and appropriate management of visual symptoms, such as convergence insufficiency or accommodative insufficiency, may mitigate the negative effects of concussion on children and adolescents and their quality of life.

OBJECTIVE: To develop an objective and easy-to-use glaucoma staging system based on visual fields (VFs). SUBJECTS AND PARTICIPANTS: A total of 13,231 VFs from 8077 subjects were used to develop models and 8024 VFs from 4445 subjects were used to validate models. METHODS: We developed an unsupervised machine learning model to identify clusters with similar VF values. We annotated the clusters based on their respective mean deviation (MD). We computed optimal MD thresholds that discriminate clusters with highest accuracy based on Bayes minimum error principle. We evaluated the accuracy of the staging system and validated findings based on an independent validation dataset. RESULTS: The unsupervised k-means algorithm discovered four clusters with 6784, 4034, 1541, and 872 VFs and average MDs of 0.0▒dB (±1.4: Standard Deviation), -4.8▒dB (±1.9), -12.2▒dB (±2.9), and -23.0▒dB (±3.8), respectively. The supervised Bayes minimum error classifier identified optimal MD thresholds of -2.2▒dB, -8.0▒dB, and -17.3▒dB for discriminating normal eyes and eyes at the early, moderate, and advanced stages of glaucoma. The accuracy of the glaucoma staging system was 94%, based on identified MD thresholds with respect to the initial k-means clusters. CONCLUSIONS: We discovered that four severity levels based on MD thresholds of -2.2▒dB, -8.0▒dB, and -17.3▒dB, provides the optimal number of severity stages based on unsupervised and supervised machine learning. This glaucoma staging system is unbiased, objective, easy-to-use, and consistent, which makes it highly suitable for use in glaucoma research and for day-to-day clinical practice.

This study defines retinal phosphatic metabolites and their adjustment to illumination in rat retinas under conditions that preserve retinal function. Metabolic data are measured using high-performance liquid chromatography (HPLC) and 31P nuclear magnetic resonance (31P NMR) spectroscopy after 10 min of light exposure in vivo compared with retinas from dark-adapted rats. Multiple high-energy and low-energy phosphatic metabolites of intermediary metabolism were quantified. The concentration of the high-energy phosphate adenosine triphosphate (ATP) remained unchanged from dark- to light-adaptation. Under the same conditions the concentrations of the high-energy phosphates guanosine triphosphate (GTP) and creatine phosphate increased, whereas the inorganic phosphate decreased. Comparing dark-adapted controls with retinas light-adapted either in vitro or in vivo, the evidence is consistent with a light-dependent increase in GTP and a decrease in cyclic guanosine monophosphate. Although cyclic adenosine monophosphate (cAMP) levels were lower in retinas light-adapted in vivo than in the dark-adapted controls, this did not seem to be an effect of light, as cAMP levels decreased similarly after 10 min incubation in dark or light in parallel with recovery of ATP/adenosine diphosphate ratios. This study: (1) reports on retinal metabolic changes with adjustment in illumination, (2) provides baseline measurements of retinal phosphatic metabolites in whole retinas, and (3) reports on the validity of chromatographic and spectroscopic methods used for studying retinal metabolism establishing a high correlation among measurements made using HPLC and 31P NMR.

Uveal melanoma is a rare form of melanoma that originates in the eye, exerts widespread therapeutic resistance and displays an inherent propensity for hepatic metastases. Since metastatic disease is characterized by poor survival, there is an unmet clinical need to identify new therapeutic targets in uveal melanoma. Here, we show that the pleiotropic cytokine midkine is expressed in uveal melanoma. Midkine expression in primary uveal melanoma significantly correlates with poor survival and is elevated in patients that develop metastatic disease. Monosomy 3 and histopathological staging parameters are associated with midkine expression. In addition, we demonstrate that midkine promotes survival, migration across a barrier of hepatic sinusoid endothelial cells and resistance to AKT/mTOR inhibition. Furthermore, midkine is secreted and mediates mTOR activation by maintaining phosphorylation of the mTOR target RPS6 in uveal melanoma cells. Therefore, midkine is identified as a uveal melanoma cell survival factor that drives metastasis and therapeutic resistance, and could be exploited as a biomarker as well as a new therapeutic target. Implications: Midkine is identified as a survival factor that drives liver metastasis and therapeutic resistance in melanoma of the eye.

PURPOSE: To determine the association of the multifocal electroretinographic (mfERG) response amplitude with the volumes of the inner, postreceptor, and photoreceptor retinal layers in the region stimulated by each mfERG element. METHODS: Sixteen healthy, young adult control subjects were studied. Each of the 103 hexagonal elements of the standard, scaled mfERG were aligned, where possible, with patches of retina imaged using optical coherence tomography. Stimuli falling on the fovea and on the optic nerve head were excluded. Linear mixed-effects modeling was then used to derive estimated coefficients (voltage/volume) for the mfERG response throughout the full 80 ms standard epoch. The resulting predicted response amplitudes originating in each layer were then compared to pharmacologically "dissected" mfERGs obtained from other studies in monkey eyes. RESULTS: Across the duration of the response, the amplitude of the modeled contribution from (1) the inner retina was small-to-modest, (2) the postreceptor retina was larger and contained two prominent peaks, and (3) the photoreceptor response was the largest and most closely paralleled the overall (i.e., intact) response, including late-appearing oscillations. The significance of each layer's contribution was greatest when the absolute amplitude of that layer's response was largest. The contribution of the inner retina was maximally significant in the interval between the prominent troughs and peaks of the intact response. The contributions of the postreceptor and photoreceptor responses were maximally significant at the prominent troughs and peaks of the intact response. CONCLUSIONS: The results of the model were in good overall agreement with previous interpretations of the cellular contributions to the mfERG. There was also fair agreement with pharmacologically dissected monkey mfERG responses. Thus, the estimations of the contributions of the retinal layers to the mfERG so produced appeared plausible.

AIM: To describe survival and neonatal morbidities in infants born before 24 weeks of gestation during a 12-year period. METHODS: Data were retrieved from national registries and validated in medical files of infants born before 24 weeks of gestation 2007-2018 in Sweden. Temporal changes were evaluated. RESULTS: In 2007-2018, 282 live births were recorded at 22 weeks and 460 at 23 weeks of gestation. Survival to discharge from hospital of infants born alive at 22 and 23 weeks increased from 20% to 38% (p = 0.006) and from 45% to 67% (p < 0.001) respectively. Caesarean section increased from 12% to 22% (p = 0.038) for infants born at 22 weeks. Neonatal morbidity rates in infants alive at 40 weeks of postmenstrual age (n = 399) were unchanged except for an increase in necrotising enterocolitis from 0 to 33% (p = 0.017) in infants born at 22 weeks of gestation. Bronchopulmonary dysplasia was more common in boys than girls, 90% versus 82% (p = 0.044). The number of infants surviving to 40 weeks doubled over time. CONCLUSION: Increased survival of infants born before 24 weeks of gestation resulted in increasing numbers of very immature infants with severe neonatal morbidities likely to have a negative impact on long-term outcome.

PURPOSE: We previously reported that archetypal analysis (AA), a type of unsupervised machine learning, identified and quantified patterns of visual field (VF) loss in idiopathic intracranial hypertension (IIH), referred to as archetypes (ATs). We assessed whether AT weight changes over time are consistent with changes in conventional global indices. We explored whether visual outcome or treatment effects are associated with select ATs and whether AA reveals residual VF defects in eyes deemed "normal" after treatment. DESIGN: Analysis of data collected from a randomized controlled trial. PARTICIPANTS: 2,862 VFs taken from 165 participants during the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT). METHODS: We applied a 14-AT model derived from IIHTT VFs. We examined changes in individual AT weights over time within all study eye VFs and evaluated differences between treatment groups. We created an AT Change score to assess overall VF change from baseline. We tested threshold baseline AT weights for association with VF outcome and treatment effect at six months. We determined the abnormal ATs with meaningful weight at outcome for VFs considered "normal" based on a mean deviation (MD) cutoff ≥-2.00 dB. MAIN OUTCOME MEASURES: Individual AT weighting coefficients, MD. RESULTS: AT1 (a normal VF pattern) showed the greatest weight change for all study eyes, increasing from 11.9% (interquartile range [IQR]: 0.44-24.1%) at baseline to 31.2% (IQR: 16.0-45.5%) at outcome (p<0.001). AT1 weight change (r=0.795, p<0.001) and a global score of AT change (r=0.988, p<0.001) correlated strongly with MD change. Study eyes with baseline AT2 (a mild diffuse VF loss pattern) weight ≥ 44% (≥1 standard deviation above the mean) showed higher AT2 weights at outcome than those with AT2 < 44% at baseline (p<0.001). Only the latter group showed a significant acetazolamide treatment effect. AA revealed residual VF loss patterns, most frequently representing mild diffuse loss and enlarged blind spot in 64 of 66 study eyes with MD ≥-2.00 dB at outcome. CONCLUSION: AA provides a quantitative approach to monitoring VF changes in IIH. Baseline AT features may be associated with treatment response and VF outcome. AA uncovers residual VF defects not otherwise revealed by MD.

PURPOSE: To elucidate risk factors for revision or removal of glaucoma drainage devices (GDD) in glaucoma patients in the United States. DESIGN: Retrospective cohort study. METHODS: IRIS® Registry (Intelligent Research in Sight) patients who underwent GDD insertion between 01/01/2013 and 12/31/2018 were included. Various demographic and clinical factors were collected. Kaplan-Meier (KM) survival plots, Cox proportional-hazard models utilizing Firth's Penalized Likelihood (CRFPL), and multivariate linear regression models were used. The main outcome measures were hazard ratios (HRs) and beta coefficient (β) estimates. RESULTS: 44,330 distinct patients underwent at least one GDD implantation, and 3,354 of these underwent subsequent GDD revision or removal surgery. With failure defined as GDD revision/removal, factors significantly associated with decreased failure included unknown race (HR=0.83; p=0.004) and unknown ethnicity (HR=0.68; p<0.001). Factors associated with increased risk of GDD revision/removal surgery included presence of chronic angle closure glaucoma (HR=1.32; p<0.001) and dry eye disease (HR=1.30; p=0.007). Additionally, factors associated with a decreased average time (in days) to GDD revision/removal included male sex (β=-25.96; p=0.044), unknown race (β=-55.28; p=0.013), and right-eye laterality (β=-38.67; p=0.026). Factors associated with an increased average time to GDD revision/removal included having a history of a past eye procedure (β=104.83; p<0.001) and being an active smoker (β=38.15; p=0.024). CONCLUSIONS: The size and scope of the IRIS Registry allows for detection of subtle associations between risk factors and GDD revision or removal surgery. Aforementioned demographic and clinical factors may all have an impact on GDD longevity and can inform the treatment options available for glaucoma patients.

BACKGROUND: Eyelid warming is an important treatment for meibomian gland dysfunction (MGD). Specialized chambered devices, using warm moist air have been developed. PURPOSE: To critically evaluate the literature on the safety and efficacy of chambered warm moist air devices in MGD treatment and pinpoint areas of future research. METHODS: PubMed and Embase were searched on 06 June 2021. The search term was '(warm OR heat OR steam OR goggle OR spectacle OR moist air) AND (meibomian OR MGD OR blepharitis OR eyelid OR dry eye OR DED)'. All relevant articles with available English full text were included. RESULTS: Eighteen articles assessing the application of chambered warm moist air eyelid warming devices were identified. In single-application studies, steam-based eyelid warming increased the eyelid temperature and improved symptoms, lipid layer thickness, and tear film breakup time (TBUT). In treatment studies, the steam-based devices improved TBUT and symptom scores. However, in the only randomized controlled trial (RCT) comparing chambered steam-based heat to hot towel treatment, there was no difference between groups for the primary outcome measure; the proportion of subjects noting symptom improvement after 4 weeks. CONCLUSION: Currently available chambered warm moist air eyelid warming devices are safe and effective at raising eyelid temperature to therapeutic levels and improving signs and symptoms of dry eye. However, it is not clear if they provide a greater benefit than other eyelid warming therapies. Further well-conducted RCTs comparing moist and dry heat devices should be conducted on patients across the range of DED severities and subtype spectrum.

Purpose: To examine patterns of standard (trabeculectomy or glaucoma drainage devices, GDDs) vs novel (minimally invasive glaucoma surgery, MIGS) surgical techniques in the US.Methods: We used the American Academy of Ophthalmology (AAO) IRIS® Registry (Intelligent Research in Sight) queried between 2013 and 2018 (inclusive) to calculate the cumulative proportion of stand-alone, concurrent (same day) or sequential (subsequent day) glaucoma surgical techniques performed in each glaucoma diagnosis type. Secondary analyses of adjusted proportions of concurrent and sequential surgeries stratified by glaucoma diagnosis were also performed.Results: Of 203,146 eyes receiving glaucoma surgeries, open angle glaucoma (OAG) was most likely to undergo all types of intervention. The iStent was the most commonly performed MIGS, primarily for those with normal tension glaucoma (NTG) or OAG (p < .001). Conversely, GDD was the most commonly performed procedure in secondary glaucoma or other (specified) glaucoma (p < .001). ECP and iStent were the most common concurrent procedures performed; most often for OAG and NTG (p < .001). After an initial standard surgery, most eyes underwent recurrent standard interventions (90.3%). ECP was the most common MIGS performed after an initial standard surgery; particularly in primary angle-closure (PACG) and secondary glaucoma eyes (p < .001).Conclusion: Glaucoma type may influence the choice of glaucoma procedures and the decision to perform concurrent as well sequential surgical procedures. Given the poorly understood long term safety and effectiveness of MIGS, and with substantially increasing use of MIGS procedures in recent years, future studies comparing their safety and effectiveness vs standard interventions, for a variety of glaucoma types, is needed.

PURPOSE: To report refractive error findings in Baltimore City schoolchildren who failed school-based vision screenings. METHODS: In this cross-sectional analysis, students pre-kindergarten through 8th grade who failed screenings during school years 2016-2019 received an eye examination, including non-cycloplegic autorefraction and visual acuity (VA) measurements. Refractive error was identified when there was at least: -0.50 diopter (D) spherical equivalent (SE) myopia, +0.50D SE hyperopia, 1.00D astigmatism, or 1.00D anisometropia in either eye. Generalized estimating equation models were used to identify factors associated with clinically significant refractive error, defined as decreased VA and more severe refractive error. RESULTS: Of 7520 students who failed screening, 6627 (88%) were analyzed. Clinically significant refractive error and any refractive error were found in 2352 (35.5%) and 5952 (89.8%) students, respectively. Mild myopia (45%, -0.50 D to <-3.00 D SE) and low astigmatism (47%, 1.00 D to <3.00 D cylinder) were the most prevalent types of refractive error. Proportions of students with myopia increased with higher grade levels (Ptrend<0.001). Myopia and astigmatism were more common in black and Latinx. Risk factors for clinically significant refractive error included higher grades (odds ratios [OR] ranged from 1.30 to 2.19 compared with 1st grade, P < .05) and Latinx ethnicity (OR = 1.31, 95%CI: 1.08-1.59). CONCLUSION: A Baltimore school-based vision program identified a substantial number of students with refractive error in a high-poverty urban community. Over 1/3 students who failed vision screening had clinically significant refractive error, with black and Latinx students at higher risk of having myopia and astigmatism.

Purpose: Localization of the lacrimal sac is a critical step during endoscopic dacryocystorhinostomy (endo-DCR). A "light pipe" can be used to transilluminate the lacrimal sac endonasally. We hypothesized that this may misguide the surgeon learning endo-DCR to create an osteotomy mostly posterior to the maxillary line if only the bone overlying the transillumination was to be removed, as the thinner lacrimal bone will transmit light more readily than the thicker maxillary bone of the frontal process of the maxilla that forms the anterior lacrimal sac fossa.Methods: The charts of 32 patients with primary acquired nasolacrimal duct obstruction in whom a lighted system was used during endo-DCR at Massachusetts Eye and Ear from April 2015 through October 2016 were reviewed. Patients with prior history of lacrimal surgery or trauma directly to the lacrimal sac fossa were excluded. Location of the maximal point of transillumination in relation to the maxillary line was observed and noted intraoperatively.Results: Of a total of 39 endo-DCR surgeries performed, the intraoperative transillumination point was entirely posterior to the maxillary line in 32 instances (82%).Conclusions: Use of an endocanalicular light pipe preferentially illuminates posterior to the maxillary line endonasally. The anterior lacrimal sac fossa (maxillary line and anterior as visualized endonasally) is rarely transilluminated, likely due to thicker bone in that region. Surgeons learning how to perform endo-DCR using a light pipe should be aware of this phenomenon.