This retrospective-prospective study aims to identify the diagnostic parameters most predictive of BSCVA in patients with OSD. Clinical, structural, and biochemical data will be collected from standard-of-care examinations and patient-reported outcome questionnaires. The goal is to determine the most informative biomarkers for visual prognosis, streamline diagnostic workflows, and support individualized management of OSD.

The study is based on the hypothesis that specific diagnostic parameters, reflecting corneal structure, ocular surface (including corneal nerve) integrity, inflammatory activity and patients' reported outcomes (questionnaires), can reliably predict BSCVA in patients with OSD. Identifying these predictors will enable evidence-based selection of diagnostic tests, streamline clinical workflows, and improve patient care efficiency.

This is a monocentric, national, retrospective-prospective, observational cohort study.

The design includes two complementary phases:

• Retrospective cohort (n = 1,500): existing clinical records will be reviewed to extract standardized diagnostic and visual acuity data.
• Prospective cohort (n = 1,000): newly enrolled patients will undergo a standardized diagnostic protocol and follow-up vists at defined time points.

No experimental interventions or off-label diagnostic procedures are included; all assessments correspond to standard-of-care examinations.

Overall study duration: Approximately 60 months. Retrospective phase: a cohort of 1,500 patients will be selected among those patients who have been visited at the Cornea Clinic of the OSR in the last 20 years (starting from 01 Jan 2005 to 31 dec 2025) and who have a follow up of at least 12 months. Prospective phase: we will enroll a cohort of 1,000 patients who will be rectruited among those visited at the Cornea Clinic of the OSR and who will be followed up for minimum 12 months. Recruitment will be ongoing for 48 months and the last patient will exit the study by month 60. Individual patient duration: up to 12 months (baseline, 6-, and 12- month visits).

Interim analyses are planned at multiple time points throughout the study, contingent on data availability and sample size progression. The precise timing of these analyses will be determined based on the pace of data collection and event occurrence, rather than fixed calendar dates.

All data will be collected using standardized, validated diagnostic methods:

• Corneal topography (maximum keratometry, Kmax) and pachymetry
• In vivo confocal microscopy (corneal nerve density and cellular morphology)
• Slit-lamp photography (conjunctival hyperemia and corneal opacity grading)
• Cochet-Bonnet esthesiometer (corneal sensitivity)
• Goldmann applanation tonometry (intraocular pressure)
• Tear cytokine quantification (including IL-1β, IL-6, TNF-α, MMP-9, multiplex immunoassay)
• Impression cytology (inflammatory cell counts)
• Ocular pain/quality of life questionnaire scores (OSDI, OPAS, VAS, VFQ25, SPEED) Retrospective data will be extracted from electronic medical records, while prospective data will be entered into a dedicated electronic case report form (eCRF) using harmonized acquisition protocols.

Inclusion Criteria:

• The participant is willing and able to provide written informed consent for study participation (prospective cohort).
• Adult participants aged ≥18 years at the time of inclusion.
• Clinically confirmed diagnosis of OSD, including but not limited to inflammatory keratopathies, neurotrophic keratopathy, exposure keratopathy, limbal stem cell deficiency, post-surgical or post-traumatic corneal alterations.
• Measurable BSCVA obtained through standardized manifest refraction and ETDRS chart testing at baseline.
• Available dataset for the diagnostic tests required by the study (e.g., corneal topography, pachymetry, confocal microscopy, corneal sensitivity testing, slit-lamp imaging, tear cytokine analysis, impression cytology).
• Willingness and ability to attend follow-up visits and complete all study-related procedures according to the study schedule.

Exclusion Criteria:

• Change of retinal, optic nerve, or macular pathology that may affect best spectacle-corrected visual acuity independently of the cornea or ocular surface (e.g., age-related macular degeneration, diabetic macular edema, optic neuropathy) in the period of study
• History of intraocular or corneal surgery within 3 months prior to baseline evaluation.
• Active intraocular inflammation, glaucoma with uncontrolled intraocular pressure, or corneal conditions not compatible with accurate imaging or measurement (e.g., severe scarring, leukoma).
• Uncontrolled systemic diseases that may impair vision or corneal health (e.g., advanced diabetes, autoimmune disease in active phase).
• Inability or unwillingness to attend follow-up visits or complete study assessments.
• Pregnant or breastfeeding women will not be enrolled, as hormonal fluctuations can alter tear film and ocular surface physiology

The study will enroll adult patients (≥18 years old) of both sexes, representative of the population affected by OSD. No restrictions will be applied regarding ethnicity or socioeconomic background