Linear instability of lid- and pressure-driven flows in channels textured with longitudinal superhydrophobic grooves

It is known that an increased flow rate can be achieved in channel flows when smooth walls are replaced by superhydrophobic surfaces. This reduces friction and increases the flux for a given driving force. Applications include thermal management in microelectronics, where a competition between convective and conductive resistance must be accounted for in order to evaluate any advantages of these surfaces. Of particular interest is the hydrodynamic stability of the underlying basic flows, something that has been largely overlooked in the literature, but is of key relevance to applications that typically base design on steady states or apparent-slip models that approximate them. We consider the global stability problem in the case where the longitudinal grooves are periodic in the spanwise direction. The flow is driven along the grooves by either the motion of a smooth upper lid or a constant pressure gradient. In the case of smooth walls, the former problem (plane Couette flow) is linearly stable at all Reynolds numbers whereas the latter (plane Poiseuille flow) becomes unstable above a relatively large Reynolds number. When grooves are present our work shows that additional instabilities arise in both cases, with critical Reynolds numbers small enough to be achievable in applications. Generally, for lid-driven flows one unstable mode is found that becomes neutral as the Reynolds number increases, indicating that the flows are inviscidly stable. For pressure-driven flows, two modes can coexist and exchange stability depending on the channel height and slip fraction. The first mode remains unstable as the Reynolds number increases and corresponds to an unstable mode of the two-dimensional Rayleigh equation, while the second mode becomes neutrally stable at infinite Reynolds numbers. Comparisons of critical Reynolds numbers with the experimental observations for pressure-driven flows of Daniello et al. (Phys. Fluids, vol. 21, issue 8, 2009, p. 085103) are encouraging.

Comparing the symmetry of upper eyelid following unilateral ptosis correction

Background Margin Reflex Distance 1(MRD 1) only describes the central height of upper eyelid and relies on the examiner’s experience and disregards eyelid contour abnormalities. Therefore MRD 1 may not be sufficient for an acceptable result to evaluate the outcomes of ptosis surgery. The primary purpose of this study was to assess outcomes of unilateral ptosis correction based on parameters including degree of symmetry, MRD 1, peak height of the upper lid, temporal and nasal ocular surface area, and temporal/nasal area ratio with an objective, quantitative, and repeatable method. Methods This study was designed as a retrospective non-randomized case-control study. Medical records of the patients with unilateral ptosis between October 2015 and December 2020 were reviewed. Patients with unilateral ptosis who underwent surgical correction and levator function of 5 mm or greater were included in the study. Two groups were defined; ptotic eye was case group and contralateral eye was control group. Data analysis was performed Image J and Matlab softwares. Results Thirty-four patients were included in the study. Mean age of patients was 58.8 ± 12.7 years (range 15–75 years). Mean follow-up time was 19.5 ± 7.3 months (range 8–40 months). Four patients were diagnosed with congenital ptosis and 30 patients aponeurotic ptosis. Mean preoperative degree of symmetry for overall eyelid contour was 36.6 ± 27.5% (range 1–92%). Mean postoperative degree of symmetry for overall eyelid contour was 72.4 ± 16.5% (range 55–92%). Temporal/Nasal (T/N) area ratios for contralateral normal eye was 1.19 pre-postoperative, and it was 1.11 preoperatively, 1.15 postoperatively for operated ptotic eye. Conclusions This study primarily demonstrated a quantitative, objective, and repeatable method to investigate the degree of symmetry after eyelid surgeries. Secondly, this study suggested that T/N ratio may not be a reliable parameter to evaluate the eyelid symmetry.

Central Retinal Artery Occlusion after Filler Injection for Upper Lid Retraction

Purpose: We report a case of central retinal artery occlusion after filler injection for upper lid retraction. Diagnosis and treatment were performed to recover visual acuity and good results.Case summary: A 40-year-old woman presented to our clinic with upper lid retraction. She was diagnosed with hyperthyroidism and thyroid orbitopathy. She had been examined regularly at a local clinic since 2016. At the first visit, her visual acuity was 1.0/1.0 and the intraocular pressure was 19 mmHg, with no unusual findings in the anterior segment. Hyaluronic acid filler was injected into the medial part of the left upper lid. As soon as the needle was removed, she complained of blurry vision and visual impairment. This was followed by the development of a relative afferent pupillary defect; her visual acuity was hand motion at 30 cm. After 5 minutes, we performed wide fundus imaging and optical coherence tomography, which revealed retinal artery occlusion and a cherry-red spot, along with inner retina hyperreflectivity. Under a diagnosis of central retinal artery occlusion, we performed anterior chamber paracentesis, intravenous mannitol and acetazole injection, and an ocular massage. Approximately 1.5 hours after filler injection, retinal artery reperfusion and loss of the cherry red spot were observed and, after about 3 hours, her vision had recovered to 1.0 from hand motion at 30 cm.Conclusions: Central retinal artery occlusion after filler injection, when diagnosed promptly, can be treated by anterior chamber paracentesis, intravenous mannitol and acetazole injection, and ocular massage.

The Influence of Sagittal Head Tilt on Periorbital Appearance: Implications for Clinical Photography and the Evaluation of Postoperative Results

Background Consistency in standardized periorbital photography – specifically, controlling for sagittal head tilt – is challenging yet critical for accurate assessment of pre and postoperative images. Objectives To systematically assess differences in topographic measurements and perceived periorbital attractiveness at varying degrees of sagittal head tilt. Methods Standardized frontal photographs were obtained from 12 female volunteers (mean age 27.5 years) with the Frankfort plane between -15 o to +15 o. Unilateral periorbital areas were cropped, and topographic measurements were obtained. The images of each individual eye, at varying head tilt, were ranked in order of attractiveness by 11 blinded evaluators. Results Inter & intrarater reliability was excellent (ICC > 0.9). Downward sagittal head tilt was linearly associated with an improved aesthetic rating (Spearman’s correlation; ρ= 0.901, p < 0.001). However, on subgroup analysis, eyes with lower lid bags received the highest aesthetic score at neutral head tilt. Pretarsal show and upper lid fold heights progressively decreased (p<0.001), positive intercanthal tilt became more pronounced (p<0.001), and the apex of the brow (p <0.001) and lid crease (p=0.036) arcs lateralized with downward sagittal head tilt, contributing to a more angular appearance of the eye. Marginal reflex distance (MRD) 1 was maintained while MRD2 progressively increased (p<0.001) with downward head tilt. Conclusions Negative sagittal head tilt significantly improves periorbital aesthetics – however, in the presence of lower eyelid bags, this also increases demarcation of the eyelid cheek junction which may be aesthetically detrimental. Controlling for sagittal head tilt is critical to reliably compare pre and postoperative clinical photographs.

Infrabrow excision to correct upper eyelid dermatochalasis in middle-aged and elderly patients

AIM: To evaluate the effects, advantages, disadvantages, and indications of infrabrow skin excision to correct upper eyelid dermatochalasis in middle-aged and elderly Chinese women. METHODS: Sixty eyelids in 30 patients were subjected to this surgical procedure from January to June 2018. All patients had upper eyelid dermatochalasis, and the functions of their levator palpebrae were all normal. The primary indications of the procedure were upper lid dermatochalasis with lateral hooding. All 30 patients underwent infrabrow skin excision at Shanxi Eye Hospital. The degree of skin relaxation before and after surgery was evaluated in all patients, and surgical outcomes and postoperative complications were also assessed. RESULTS: All patients were female, ranging from 40 to 64 (mean: 53.20±7.10) years old. Skin relaxation of the upper eyelid was improved in all 30 patients. One month after the operation, 52 lids (86.7%) showed good results and 8 lids (13.33%) showed fair results. The objective Strasser system was applied to evaluate surgical results at 1 and 6 months. All patients had scores between 0 and 1 point, indicating good results. Preoperative unsatisfactory position and shape of the eyebrows were improved, and crow's feet and frontal lines were reduced. All patients were satisfied with the results. No complications related to wound dehiscence, lagophthalmos, or hypertrophic scars were observed. CONCLUSION: Infrabrow skin excision is a simple, useful operation to reconstruct the upper eyelids in selected patients of Chinese ancestry. This procedure not only retains the advantages of classic blepharoplasty, but also alleviates many eyebrow problems at the same time, and maintains the original shape of the eyelid, minimizes scarring, and produces a smoother, more youthful appearance.

Applicability of a sheep model for training in plastic surgery of eyelids and orbit

Objective To test the applicability of a fresh tissue model for teaching facial plastic techniques and approaches to the eyelids and orbit. Design Observational animal experiments. Subjects Ten prepubescent sheep heads harvested following humane euthanasia at the completion of unrelated live animal research. Methods Young sheep were saline perfused at the end of an in vivo protocol. Head and neck tissues were harvested and refrigerated for 3–7 days. An experienced oculoplastic surgeon and an otolaryngologist explored the feasibility of common oculoplastic procedures in the ovine model. Results The model has potential for teaching basic principles in eyelid surgery including upper lid blepharoplasty, aponeurotic ptosis repair, upper lid gold weight lid loading for facial paralysis, lateral canthotomy and inferior limb cantholysis, lower lid tightening, and transconjunctival approach to the orbital floor. Eye muscle advancement, optic nerve sheath fenestration, and enucleation also accurately simulated human surgery. Anatomic variations limit the sheep model for orbital floor reconstruction and lacrimal drainage procedures. Conclusions The sheep head and neck provide an inexpensive, safe model for developing skills in several oculoplastic procedures. Formal simulation testing is needed to confirm these expert opinions.

Excellent Healing after Severe Lid Injury by a Bird

Eye lid lacerations secondary to penetrating trauma is quite common. Most of the injuries occur due to animal bites, falls and collision with sharp objects. They may lead to partial or full thickness lid defects. We report a case of middle aged woman who was attacked by bird claws and sustained severe upper lid laceration that was immediately thoroughly investigated and then managed surgically resulting in excellent wound healing. Ocular trauma from bird pecking injury can cause blindness in humans. The public should guard against feeding and keeping close with them. If immediate medical attention is given by the ophthalmologist and urgent primary repair is done there are high chances to save the eye from disastrous complications. Key Words: Lid laceration, ocular trauma, penetrating injury.

Safety and Efficacy of Topical Lotilaner Ophthalmic Solution 0.25% for the Treatment of Demodex Blepharitis: A Pilot Study

Purpose. Evaluate safety and efficacy of topical lotilaner ophthalmic solution, 0.25% for the treatment of Demodex blepharitis. Patients and Methods. 15 patients with Demodex blepharitis, defined as >10 collarettes on the upper lid, lid margin erythema, and Demodex density of ≥1.5 mites/lash on microscopy, were treated bid for 28 days with lotilaner ophthalmic solution, 0.25%. Contact lens wear, artificial eyelashes, and lid structural abnormalities were among the exclusion criteria. No other antibacterial, antiparasitic, or anti-inflammatory treatment or lid hygiene products were permitted. Patients were assessed on Days 7, 14, 28, 60, and 90. Outcome measures were changes in collarette grade and mite density on Day 28. Adverse events and changes in intraocular pressure (IOP), corrected distance visual acuity (CDVA), and slit-lamp biomicroscopy were assessed. Results. Mean collarette grade (upper lids) improved from 3.07 ± 0.21 to 0.79 ± 0.19 on Day 28; the change was statistically significant for both upper and lower lids from Day 14 on. Mean mite density per lash decreased from 2.28 ± 0.16 at baseline to 0.14 ± 0.05 at Day 28 p < 0.0001 . Mite eradication (0 mites) was documented in 57.1% of eyes. The effects were durable through Day 90. There were no adverse events and little to no change in CDVA or IOP. The drop was well tolerated, with no discontinuations due to ocular irritation. Conclusion. Topical lotilaner ophthalmic solution, 0.25% for 4 weeks, showed promising efficacy for the treatment of Demodex blepharitis. This novel treatment appears to be safe and well tolerated. Randomized controlled studies are needed to confirm the results.

Effectiveness of eye-light therapy in improving dry eye symptoms

: We aimed to examine the effectiveness of eye-light therapy in improving the dry eye symptoms.: The retrospective case series where patients who underwent eye-light therapy between March 2019 to May 2020 were analyzed. Twenty patients aged ≥18 years with dry eyes were included. Patients with ocular infections, complications, contact lens users and missing data were excluded. OSDI scores and tear parameters such as noninvasive break up time (NIBUT), lipid layer thickness (LLT), tear meniscus height, meibography of upper and lower lid were evaluated pre and post one month Eye-Light therapy.: Twenty patients with mean±SD age of 43.55±20.53 years and mean spherical equivalent refractive error of 0.69±1.79 diopters were analyzed. OSDI was significantly associated with NBUT (r=-0.50, P = 0.02), lipid layer thickness (r=-0.45, P=0.047) and tear height (r =-0.45, P=0.046). OSDI was positively associated with upper lid meibography (r=0.74, P=&#60;0.001) and lower lid meibography (r=0.45, P=0.045). Post-therapy, reduction in OSDI score post-therapy was present, NBUT was similar, lipid layer thickness and tear height were increased, meibography of upper lid was reduced, and meibography of lower lid did not alter much. Eye-light therapy is effective in reducing dry eye related symptoms with minimal immediate effect on tear film parameters post therapy. Eye-light therapy acts as an adjunct to ameliorate MGD. MGD being a chronic disease requires sustained therapy with environmental changes. Long term evaluation is required to assess the tear film changes and the pattern of efficacy of light therapy.

Eyes wide shut: necessity and effect of adjunctive procedures after decompression surgery in patients with endocrine orbitopathy

Background Orbital decompression surgery is frequently the last therapeutic measure in the surgical treatment of endocrine orbitopathy (EO). Additional rehabilitative and corrective surgical treatments are often used to improve the resulting eyelid stigmata, such as an increased lid aperture and scleral show. The aim of the study was to evaluate the effect of adjunctive surgical procedures after orbital decompression surgery in patients with EO. Methods A total of 120 orbitae from 65 patients with EO from 2010 to 2020 at a tertiary care center in Germany were retrospectively evaluated. Ocular surface area (OSA) and vertical palpebral fissures were three-dimensionally analyzed at the following stages: presurgical decompression, postsurgical decompression, and post-adjunctive surgical procedures. For the analysis of vertical palpebral fissures, predefined vertical line distances were measured on the upper and lower lids in the central, medial, and lateral pupillary regions. Results The initial OSA was 2,98 ± 0.85 cm2, and it decreased significantly after decompression surgery to 2.52 ± 0.62 cm2. After adjunct surgical procedures, OSA further decreased to 2,31 ± 0,55 cm2. Furthermore, a statistically significant reduction in all pupillary parameters was noted after each treatment step. More lid-lengthening procedures were performed on the lower lid than on the upper lid. Canthoplasty (n = 13) was the most frequently performed procedure during rehabilitation. Conclusion Surgical decompression surgery improves OSA and leads to a significant reduction in lid aperture. Adjunctive surgical procedures, addressing the upper and lower lid, have a significant influence on the ongoing clinical course and contribute to a reduction in OSA.