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This review aimed to evidence the predisposing conditions for Salzmann nodular degeneration (SND), where particular attention was paid to its association with ocular and systemic diseases. SND is a rare disease characterized by bluish-white nodules located in the mid-periphery of the cornea, which are otherwise completely clear. SND has been found in association with different systemic and ocular diseases, and it may have unilateral or bilateral presentation. Initial forms are only diagnosed occasionally as they are asymptomatic, whereas, in advanced disease, the visual acuity might be seriously impaired. Although SND is well described, its exact etiopathology is currently still unknown and is frequently misdiagnosed. It is associated with ocular surface inflammatory conditions and previous corneal surgery, and it has been described in different systemic diseases. Diagnosis is clinically based with slit lamp examinations, and instrumental assessments with corneal topography permit one to observe the alterations of the corneal profile, whereas anterior segment–optical coherence tomography (AS-OCT) is used to investigate the stromal depth of the nodules. Therapy might be conservative with the objective of improving the ocular surface homeostasis and surgical outcomes, where the aim is to restore the corneal regularity and visual acuity. Ophthalmologists should pay particular attention when detecting nodules in patients with ocular and non-ocular inflammatory diseases to guarantee the patient a timely diagnosis and a better therapeutic outcome. Additionally, collaboration between specialists who deal with treating patients suffering from disorders potentially associated with SND is recommended. [ABSTRACT FROM AUTHOR]

The identification of new biomarkers of ocular diseases is nowadays of outmost importance both for early diagnosis and treatment. Epigenetics is a rapidly growing emerging area of research and its involvement in the pathophysiology of ocular disease and regulatory mechanisms is of undisputable importance for diagnostic purposes. Environmental changes may impact the ocular surface, and the knowledge of induced epigenetic changes might help to elucidate the mechanisms of ocular surface disorders. In this pilot study, we investigated the impact of extensive contact lens (CL) wearing on human corneal epithelium epigenetics. We performed ex vivo analysis of the expression of the miR-320 and miR-423-5p involved in the processes of cellular apoptosis and chronic inflammation. The human corneal epithelium was harvested from healthy patients before the photorefractive keratectomy (PRK). The patients were divided into two age- and sex-matched groups accordingly to CL wearing history with no CL wearers used as a control. The epithelium was stored frozen in dry ice at −80 °C and forwarded for miRNA extraction; afterwards, miRNA levels were detected using real-time PCR. Both miRNAs were highly expressed in CL wearers (p < 0.001), suggesting epigenetic modifications occurring in chronic ocular surface stress. These preliminary results show the relationships between selected miRNA expression and the chronic ocular surface stress associated with extensive CL use. MicroRNAs might be considered as biomarkers for the diagnosis of ocular surface conditions and the impact of environmental factors on ocular surface epigenetic. Furthermore, they might be considered as new therapeutic targets in ocular surface diseases. [ABSTRACT FROM AUTHOR]

Keratoconus results in an increase in anterior and posterior curvatures and a reduction in corneal thickness. Anterior corneal ectasia is partially compensated by remodelling the corneal epithelium. Therefore, there is an alteration in the relationship between corneal surfaces and variation in corneal power. The variation in corneal power is one of the sources that induces errors in IOL power calculation. This study aimed to assess a method for predicting total corneal power in keratoconus using several anterior surface parameters at 3 mm and 4 mm. Tomographic data obtained using Pentacam (Oculus, Germany) were analysed from 280 eyes of 140 patients with keratoconus using anterior and posterior keratometry, anterior Q-value at 8 mm, central corneal thickness, Kmax location and value, and true net power at 4 mm (TNP). Calculated total corneal power (TCPc) at 3 mm was obtained using the Gauss formula. Predicted total corneal power at 3 mm (TCPp3) and 4 mm (TCPp4) was obtained from univariate (TCPp3u and TCPp4u) and multivariate linear regression formulae (TCPp3m and TCPp4m). SimK, anterior Q-value, vertical location, and Kmax value were used in the multivariate formulae. Mean absolute error (MAE) and median absolute error (MedAE) were also calculated. Absolute frequencies within dioptric ranges of all formulas divided for keratoconus grading were evaluated. TCPc and TNP exhibited a good correlation (R2 = 0.58, p < 0.05) with a higher dispersion above 50 D of corneal power. Highly significant correlations were observed between TCPp3u and TCPc (R2 = 0.978, p < 0.05) and TCPp3m and TCPc (R2 = 0.989, p < 0.05). Lower but significant correlations were observed between TCPp4u and TNP (R2 = 0.692, p < 0.05) and between TCPp4m and TNP (R2 = 0.887, p < 0.05). The best results for TCP prediction at 3 and 4 mm were obtained with TCPp3m and TCPp4m as follows: MAE of TCPp3m was 0.24 ± 0.20 (SD) D with MedAE of 0.20 D, while MAE of TCPp4m was 0.96 ± 0.77 D with MedAE of 0.80 D. The 3 mm multivariate regression formula results in higher absolute frequencies of prediction errors in the total eyes within 0.5 D (93%) than the univariate formula (81%). At 4mm, the multivariate regression formula has a lower percentage within 0.5 D (32%) than the univariate formula (41%), but the percentage of the multivariate formula is higher within 1 D (63%) than the univariate formula (56%). All formulas show a decrease in accuracy with increasing grades of keratoconus. Multivariate linear regression formulae using only anterior surface data can predict TCP with good approximation in eyes with keratoconus in cases where posterior surface parameters are unavailable. The vertical location of Kmax and the anterior asphericity could play a relevant role in the prediction of total corneal power in keratoconus. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical characteristics of pediatric patients with progression of keratoconus after accelerated iontophoresis-assisted epithelium-on corneal cross-linking (I-ON CXL) and to assess the efficacy and safety of re-treatment using accelerated epithelium-off CXL (epi-OFF CXL). Methods: Sixteen eyes of 16 patients (mean age: 14.6 ± 2.5 years) with keratoconus underwent I-ON CXL. The main outcome measures were uncorrected distance visual acuity, corrected distance visual acuity, maximum keratometry index (Kmax), minimum corneal thickness, elevation front and elevation back measured at the thinnest point, total higher order aberrations root main square (HOA RMS), coma RMS, and spherical aberration. An increment of Kmax greater than 1.00 diopter (D) and a decrease of greater than 20 µm in pachymetry were considered to determine the progression of keratoconus. Patients with progression of keratoconus after I-ON CXL were re-treated using an epi-OFF CXL protocol. Results: Two years after I-ON CXL, 12 patients showed progression of keratoconus, whereas 4 patients were stable. There was significant worsening of Kmax (P =.04) and steepest keratometric reading (P =.01). Furthermore, a significant correlation was documented between progression of keratoconus and age (P =.02). These patients were re-treated using an epi-OFF protocol and after 2 years all patients were stable, and a statistically significant reduction of the mean Kmax (P =.007), HOA RMS (P =.05), and coma RMS (P = 05) was observed. Conclusions: I-ON CXL was ineffective in the treatment of pediatric keratoconus in younger children, whereas it had an efficacy of 2 years in older children. Re-treatment using epi-OFF CXL proved effective to halt progression of keratoconus after I-ON CXL failure. [J Pediatr Ophthalmol Strabismus. 2024;61(1):44–50.] [ABSTRACT FROM AUTHOR]

Femtosecond laser (FSL) is an infrared laser with a wavelength of 1053 nm. FS laser works producing photodisruption or photoionization of the optically transparent tissue such as cornea. Currently FS lasers have a wide range of applications in ophthalmic surgery. They are used above all in corneal surgery in refractive procedures and keratoplasty, and recently in cataract surgery. The use of the FSL in corneal refractive surgery includes LASIK flap creation, astigmatic keratotomy, Femtosecond Lenticule Extraction (FLEx), Small Incision Lenticule Extraction (SMILE) and channels creation for implantation of the intrastromal corneal rings. As to the corneal grafting, the FS lasers are used in laser-assisted anterior and posterior lamellar keratoplasty and customized trephination in the penetrating keratoplasty. FS Laser Assisted Cataract Surgery (FLACS) includes capsulorrhexis and nuclear fragmentation that enhance safety and efficacy of the procedure.

This study investigates mechanisms of adaptation to metal toxicity peculiar to the midgut epithelium of Epilachna cf. nylanderi (Mulsant, 1850) (Coccinellidae). This species of beetle has currently been identified in only one locality in South Africa and is known to feed on the nickel hyperaccumulator Berkheya coddii Roessl. (Asteraceae), an endemic plant species of the South African ultramafic ecosystem. Our focus involves an analysis of the morphological features of cells forming the midgut epithelium, which is the first organ exposed to toxic levels of metals ingested by the insect. Through the three key processes of apoptosis, necrosis, and autophagy, excess metals are eliminated from the organism and homeostatic conditions are maintained. Apoptosis and necrosis are both known to be involved in the degradation of midgut epithelial cells, while the role of autophagy is mainly implicated in the disintegration of the organelles of cells. This study reports on the participation of these three key degenerative processes in the removal of excess metals based on targeted observations of the insect midgut epithelium by light and electron microscopies. Additionally, the TUNEL reaction was specifically used to detect apoptosis. Notre etude explore les mecanismes d'adaptation la toxicite des metaux specifiques l'epithelium du tube digestif moyen d'Epilachna cf. nylanderi (Mulsant, 1850) (Coccinellidae). Cette espece de coleoptere a ete actuellement retrouvee dans une seule localite d'Afrique du Sud et est connue pour s'alimenter de Berkheya coddii Roessl. (Asteraceae), une plante hyperaccumulatrice de nickel et endemique l'ecosysteme ultramafique de l'Afrique du Sud. Notre etude se concentre sur l'analyse des caracteristiques morphologiques des cellules qui forment l'epithelium du tube digestif moyen, le premier organe etre expose aux niveaux toxiques des metaux ingeres par l'insecte. A travers les trois processus essentiels d'apoptose, de necrose et d'autophagie, les metaux excedentaires sont elimines de l'organisme et les conditions homeostatiques maintenues. L'apoptose et la necrose sont toutes deux connues comme etant impliquees dans la degradation des cellules epitheliales du tube digestif moyen, alors que l'autophagie est surtout impliquee dans la desintegration des organites cellulaires. Notre etude decrit la participation de ces trois processus de degenerescence essentiels au retrait des metaux excedentaires partir d'observations ciblees de l'epithelium du tube digestif moyen par microscopies photonique et electronique. De plus, nous avons utilise la reaction TUNEL specifiquement pour detecter l'apoptose. [Traduit par la Redaction], Introduction Plants that accumulate metals may use them in protective mechanisms against herbivory and fungal attacks (Boyd 2007). However, some herbivorous insect species have adapted themselves to using these plants [...]