Objective: Pseudoexfoliation syndrome (PEX) is an age-related systemic disorder characterised by the deposition of extracellular fibrillar material in ocular tissues, particularly the lens capsule, pupillary margin, and trabecular meshwork. PEX is a major risk factor for glaucoma and elevated intraocular pressure (IOP), but its independent effect on corneal endothelial morphology remains uncertain. Previous studies have reported inconsistent findings regarding endothelial cell density (ECD), morphology, and central corneal thickness (CCT). This study aimed to evaluate the impact of PEX on endothelial morphology and CCT using non-contact specular microscopy in a Portuguese cohort.

Material and methods: We conducted a retrospective cross-sectional study including 450 eyes: 250 with PEX and 200 age-matched controls without PEX. Eyes with pre-existing corneal disease, prior intraocular surgery, or contact lens wear were excluded. PEX was diagnosed by slit-lamp biomicroscopy, and IOP was measured by Goldmann applanation tonometry. Endothelial parameters were assessed with the EM-3000 specular microscope, including cell count, ECD, mean cell area, coefficient of variation (CV), hexagonality, and CCT. Group differences were analysed using parametric and non-parametric tests, with ANCOVA adjusting for age, sex, and IOP.

Results: Baseline characteristics were comparable for age (PEX: 76.2 ± 6.9 years; controls: 75.9 ± 6.1 years; p = 0.289) and sex (female: 56.4% vs. 55.5%; p = 0.521). Glaucoma and ocular hypertension were more frequent in PEX (35.5% and 5.2%, respectively) compared with controls (3.9% and 0%; p < 0.001). On unadjusted analysis, ECD was lower in PEX eyes (2389.2 ± 305.7 vs. 2461.8 ± 274.1 cells/mm²; p = 0.042), though the difference attenuated after adjustment (p = 0.055). Mean cell area was larger in PEX (417.0 µm² [IQR 386.0–452.0] vs. 410.5 µm² [381.0–439.0]) and reached significance after adjustment (p = 0.036). CV was slightly lower in PEX (37.8% [35.0–42.5] vs. 40.9% [36.5–45.0]; p = 0.029), persisting after adjustment (p = 0.031). Hexagonality did not differ between groups. CCT was significantly greater in PEX (541.0 ± 35.9 vs. 530.2 ± 36.8 µm; p = 0.029), remaining significant after adjustment (p = 0.041).

Conclusion: PEX was associated with subtle but clinically relevant corneal endothelial changes, including a trend toward reduced ECD, larger cell area, lower CV, and increased CCT. These alterations persisted for CCT, CV, and cell area after adjustment for age, sex, and IOP. The higher prevalence of glaucoma and ocular hypertension in PEX further reinforces the need for careful preoperative assessment. Specular microscopy should be considered routine in PEX patients to anticipate surgical risks and guide management.

Keywords: cornea, endothelium, corneal, pseudoexfoliation syndrome, ocular hypertension, glaucoma

PEX, pseudoexfoliation syndrome; IOP, intraocular pressure; ECD, endothelial cell density; CCT, central corneal thickness; CV, coefficient of variation; SD, standard deviation

Pseudoexfoliation syndrome (PEX) is an age-related systemic disorder characterised by the progressive accumulation of fibrillar extracellular material in ocular and extraocular tissues.^1–3 In the anterior segment, deposits are typically seen on the anterior lens capsule, pupillary margin, zonular apparatus, and trabecular meshwork, where they contribute to zonular weakness, poor pupillary dilation, and secondary open-angle glaucoma.^3–5 PEX is one of the most common identifiable causes of secondary glaucoma worldwide and is of particular importance in cataract surgery, where the coexistence of zonular instability and raised intraocular pressure (IOP) increases surgical complexity and risk of complications.^4,5

The corneal endothelium, a non-regenerating monolayer critical for maintaining corneal clarity and hydration, may also be affected in PEX.³ Ultrastructural studies have shown deposits of pseudoexfoliative material on the endothelial surface, and clinical investigations using specular microscopy have evaluated its impact on endothelial cell density (ECD) and morphology.^3,6–8 However, the results are inconsistent. Several reports describe reduced ECD and increased cell size variability in PEX compared to controls, while others find no significant differences, particularly in the absence of glaucoma. Morphological indices such as polymegathism and pleomorphism have also yielded variable findings across studies.^3,8,9

The relationship between PEX and central corneal thickness (CCT) is similarly debated. Some studies suggest thicker corneas in PEX, others report thinning, and many show no significant change.^3,6–10 Differences in study design, population characteristics, and adjustment for IOP or glaucoma may partly explain this heterogeneity. Importantly, most prior investigations have been conducted in Nordic, Middle Eastern, or Asian populations, and relatively few data exist from Southern European cohorts. Since endothelial reserve and corneal thickness directly influence surgical risk, clarifying the impact of PEX on these parameters has practical clinical relevance.^5,7

Another limitation of the literature is the inconsistent adjustment for confounding variables such as age, sex, and IOP. Given that PEX is strongly associated with ocular hypertension and glaucoma, studies that do not control for IOP may conflate pressure-related endothelial damage with the independent effect of PEX itself. This distinction is important, as endothelial compromise may alter decision-making not only for cataract surgery but also for glaucoma interventions, intraocular lens selection, and postoperative monitoring.^3,4,6

Against this background, the present study sought to evaluate corneal endothelial parameters and CCT in a Portuguese population with and without PEX, using non-contact specular microscopy. By applying adjusted analyses that account for age, sex, and IOP, we aimed to clarify whether PEX is independently associated with measurable alterations in endothelial morphology and thickness.

Study design and participants

We conducted a retrospective, cross-sectional study at the Ophthalmology Department, Unidade Local de Saúde Entre Douro e Vouga, Santa Maria da Feira, Portugal. Consecutive patients with clinically confirmed PEX were compared with age-matched controls without PEX, examined during the same study period. Eyes were eligible if no pre-existing corneal pathology was present and clear specular microscopy images could be obtained. Exclusion criteria included history of intraocular surgery or trauma, contact lens wear, and corneal dystrophy or degeneration. When both eyes of a patient met inclusion criteria, one was randomly selected for analysis to avoid inter-eye correlation.

Ethics: The study adhered to the tenets of the Declaration of Helsinki. Given the retrospective design and use of anonymised data, the requirement for written informed consent was waived by the Institutional Review Board.

Demographic and clinical variables

Age and sex were recorded. PEX diagnosis was made by slit-lamp biomicroscopy by a corneal specialist, based on the presence of characteristic deposits at the pupillary margin and/or anterior lens capsule. IOP was measured by Goldmann applanation tonometry and classified as normotensive, ocular hypertension, or glaucoma based on contemporaneous clinical records.

Specular microscopy

Central corneal endothelial imaging and pachymetry were obtained using the EM-3000 non-contact specular microscope (Tomey GmbH, Erlangen, Germany), following the manufacturers protocol. Parameters included: endothelial cell count (n), ECD (cells/mm²), mean cell area (µm²), standard deviation (SD) of cell area, coefficient of variation (CV; %), hexagonality (% of six-sided cells), and CCT (µm).

Statistical analysis

All statistical analyses were performed using SPSS Statistics, version 30.0 (IBM Corp., Armonk, NY, USA). Data distribution was tested with the Shapiro–Wilk test. Normally distributed continuous variables were expressed as mean ± SD, while skewed variables were expressed as median [interquartile range]. Categorical variables were summarised as counts and percentages. Group comparisons were made using independent samples t-test or Mann–Whitney U test for continuous variables and χ² or Fisher’s exact test for categorical variables. Analysis of covariance (ANCOVA) was applied to assess differences in key endpoints (ECD, mean cell area, CV, hexagonality, and CCT), with adjustment for age, sex, and IOP category. A two-sided p-value <0.05 was considered statistically significant.

Study population

A total of 450 eyes were analysed: 250 with PEX and 200 controls without PEX. Baseline demographic characteristics are summarised in Table 1. The mean age of participants was similar between groups (PEX: 76.2 ± 6.9 years; controls: 75.9 ± 6.1 years; p = 0.289). Females accounted for 56.4% of the PEX group and 55.5% of the controls (p = 0.521).

Intraocular pressure (IOP) stratification differed significantly between groups (Table 1). Among PEX eyes, 59.3% were normotensive, 5.2% had ocular hypertension, and 35.5% had glaucoma. In contrast, 96.1% of controls were normotensive and 3.9% had glaucoma, with no cases of ocular hypertension. The overall distribution of IOP categories was significantly different (p < 0.001).

Endothelial cell parameters

Specular microscopy findings are presented in Table 2. On unadjusted analysis, PEX eyes demonstrated lower mean ECD compared with controls (2389.2 ± 305.7 vs. 2461.8 ± 274.1 cells/mm²; p = 0.042). The mean cell area was larger in the PEX group (median 417.0 µm² [IQR 386.0–452.0]) compared with controls (410.5 µm² [381.0–439.0]), but this difference did not reach statistical significance (p = 0.101). The CV of cell size was slightly lower in PEX eyes (median 37.8% [35.0–42.5]) than in controls (40.9% [36.5–45.0]; p = 0.029). Hexagonality was similar between groups (median 49.5% vs. 49.0%; p = 0.894). The standard deviation of mean cell area did not differ significantly between groups. CCT was significantly greater in PEX eyes compared with controls (541.0 ± 35.9 vs. 530.2 ± 36.8 µm; p = 0.029).

Adjusted analysis

After adjustment for age, sex, and IOP category using ANCOVA (Table 2), differences in CCT (p = 0.041) and CV (p = 0.031) remained statistically significant. The increase in mean cell area in PEX also reached significance after adjustment (p = 0.036). The reduction in ECD attenuated to borderline significance (p = 0.055), while no significant differences were observed for hexagonality or SD of cell area.

This study evaluated the corneal endothelium in a Portuguese cohort of patients with PEX compared with age-matched controls, using non-contact specular microscopy. The principal findings were:

1. PEX eyes had lower endothelial cell density, although this difference attenuated to borderline significance after adjustment
2. Mean cell area was larger in PEX and reached statistical significance after adjustment
3. The coefficient of variation was lower in PEX, in contrast to some prior reports
4. Central corneal thickness was significantly greater in PEX, even after adjustment
5. The prevalence of ocular hypertension and glaucoma was substantially higher in PEX eyes.

Comparison with previous studies

Our results add to the growing but heterogeneous literature on corneal endothelium in PEX. Several specular and confocal microscopy studies have reported reduced ECD in PEX eyes. Songur et al. demonstrated significantly lower ECD in Turkish PEX patients compared to controls, particularly in those with concomitant glaucoma.⁸ Sarowa et al. also observed both qualitative (pleomorphism, polymegathism) and quantitative (ECD loss) changes in PEX and pseudoexfoliation glaucoma (PEXG).¹¹ Aoki and colleagues, in a large Japanese series, identified PEX as an independent risk factor for endothelial cell loss, even when accounting for age and IOP.⁷

Conversely, Bozkurt et al. found no significant ECD difference between PEX and senile cataract eyes,⁹ while other smaller series also failed to detect measurable endothelial compromise in the absence of glaucoma,¹² suggesting population-specific variability or differences in disease severity. This inconsistency mirrors our own finding that while ECD was lower in PEX, significance weakened after adjustment. It underscores the importance of carefully controlling for confounders such as age and IOP, which may partly explain conflicting results in the literature. The latter is especially relevant given that glaucoma prevalence in our PEX cohort was over eightfold higher than in controls, consistent with epidemiologic data from multiple populations.⁴ Our findings raise the question of whether endothelial alterations in PEX eyes result from pseudoexfoliative material itself or secondary effects of glaucoma and elevated IOP. Both mechanisms likely contribute. Glaucoma, regardless of cause, is known to reduce ECD through chronic IOP stress and long-term exposure to topical medications containing preservatives.^1–3 In our cohort, the higher prevalence of glaucoma and ocular hypertension among PEX patients may have influenced endothelial parameters. However, the persistence of significant differences in mean cell area, CV, and CCT after adjusting for IOP suggests that PEX may also exert a direct, independent effect on the endothelium. Experimental studies showing pseudoexfoliative deposits on Descemet’s membrane and within endothelial cells support this possibility.^4–6

Morphological indices have also shown mixed results. Many authors report increased polymegathism (higher CV) and reduced hexagonality in PEX.^11–13 Confocal microscopy has revealed irregular cell borders and increased dark spots, possibly reflecting cellular stress.⁶ By contrast, we observed a lower CV in PEX and no significant difference in hexagonality. While this divergence may represent population-specific variation, technical factors are also likely contributors. For example, automatic versus manual cell tracing, image quality thresholds, and device algorithms can significantly influence CV calculations.^9,11 Furthermore, cross-sectional design cannot capture dynamic processes; transient remodelling of cell borders might not be detected in static assessments. Notably, our results suggest that not all morphometric indices are equally sensitive to PEX-related endothelial stress, and further multicentre validation is warranted.

The association between PEX and CCT remains unsettled. Studies from Kashmir reported thinner corneas in PEX, especially when glaucoma was present.¹⁰ Similar findings have been described in Turkish populations, suggesting that PEX may exacerbate the CCT thinning already associated with elevated IOP.¹⁴ Conversely, other groups, including Songur et al.,⁸ observed no difference, while Akdemir et al.¹⁴ even reported thicker corneas in PEX, hypothesising an effect of PEX-related ocular surface disease.

Our results showed significantly thicker corneas in PEX eyes, consistent with Akdemir’s observation and in contrast to the Kashmir data. Possible explanations include ethnic or regional differences, environmental factors, or methodological issues such as ultrasound pachymetry versus specular-derived measurements. Our findings support the possibility that PEX may be associated with increased corneal thickness in some populations, although clinical implications—particularly for IOP interpretation—remain to be clarified.

Clinical implications

The clinical significance of our findings lies primarily in surgical planning. PEX is a well-established risk factor for intraoperative complications in cataract surgery due to poor pupillary dilation, zonular fragility, and increased capsular instability.^5,7,15 Lower ECD and morphologic irregularities, even if modest, may further increase the risk of corneal decompensation, particularly in cases with coexisting glaucoma or elevated IOP. This is especially relevant in modern phacoemulsification techniques, where endothelial reserve is critical to withstand ultrasound energy and fluid turbulence.

Several recent studies have examined endothelial outcomes after phacoemulsification in PEX. Asfuroglu and Kemer found that CCT and corneal volume changes were more pronounced postoperatively in PEX eyes, highlighting greater surgical vulnerability.¹¹

Sarowa et al. also reported accelerated endothelial cell loss in PEXG following cataract extraction.¹¹ These observations reinforce the need for preoperative endothelial assessment, cautious fluidics, and consideration of adjunctive protective strategies (e.g. dispersive viscoelastics, modified chop techniques) in PEX patients.^5,15

Beyond cataract surgery, PEX eyes undergoing trabeculectomy, tube implantation, or keratoplasty may be at higher risk of endothelial compromise. Aoki et al. identified PEX as a risk factor for corneal decompensation after Descemet’s membrane endothelial keratoplasty, and recent systematic reviews emphasise PEX as a predictor of intraoperative complication rates.^5,7,16,17 Thus, our findings of subtle but significant endothelial changes further support the inclusion of specular microscopy in the routine preoperative evaluation of PEX patients.

Strengths and limitations

Strengths of the present study include the relatively large cohort size, the use of age-matched controls, and the application of adjusted analyses that accounted for major confounders. To our knowledge, this is the first study to report on PEX and corneal endothelium in a Portuguese population, contributing data from Southern Europe, which is underrepresented in the literature.

Limitations include the retrospective design and single-centre setting, which may restrict generalisability. Medication history, particularly chronic topical therapy containing preservatives such as benzalkonium chloride, was not controlled for and could influence endothelial status. Only central endothelial parameters were evaluated, although peripheral involvement may be more pronounced in PEX. Finally, cross-sectional design precludes evaluation of longitudinal changes; prospective studies are needed to determine whether PEX independently accelerates endothelial loss over time.

Future directions

Future research should focus on prospective, longitudinal evaluation of endothelial dynamics in PEX, ideally stratified by glaucoma status and IOP control. Multicentre collaborations would allow larger sample sizes and exploration of ethnic and regional variability. In addition, integrating advanced imaging techniques such as in vivo confocal microscopy could provide deeper insight into cellular and subcellular changes. Finally, studies correlating ocular and systemic manifestations of PEX may clarify whether corneal endothelium can serve as a surrogate marker for broader disease severity.

In summary, PEX was associated with subtle but clinically relevant alterations in corneal endothelial parameters and increased CCT in this Portuguese cohort. These findings highlight the need for careful preoperative endothelial evaluation in PEX patients and suggest that regional and methodological differences may partly explain the heterogeneity of published results. Future prospective, multicentre studies are warranted to clarify the true magnitude and clinical significance of endothelial involvement in PEX.

None.

Author contributions

The study conception and design were performed by João Alves Ambrósio, Pedro Cardoso Teixeira, Jeniffer Jesus, Catarina Pestana Aguiar, and Inês Almeida. Literature search, data acquisition and analysis, and manuscript preparation were conducted by João Alves Ambrósio. All authors commented on and approved the final version of the manuscript.

Data Availability

De-identified data and analysis code available upon reasonable request to the corresponding author.

The authors declare that there are no conflicts of interest.

No funding or sponsorship was received for the conduct of this study.

1. Bora RR, Prasad R, Mathurkar S, et al. Cardiovascular manifestations of pseudoexfoliation syndrome: a narrative review. Cureus. 2024;16(1):e51492.
2. Patil VR, Vallabha K, Wali K. Systemic vascular parameters in ocular pseudoexfoliation. Cureus. 2024;6(6):e62933.
3. Thomas MN, Skopiński P, Roberts H, et al. The ocular surface and the anterior segment of the eye in the pseudoexfoliation syndrome: a comprehensive review. Int J Mol Sci. 2025;26(2):532.
4. Anastasopoulos E, Founti P, Topouzis F. Update on pseudoexfoliation syndrome pathogenesis and associations with intraocular pressure, glaucoma and systemic diseases. Curr Opin Ophthalmol. 2015;26(2):82–89.
5. Preoteasa LD, Baltă G, Baltă FN. Investigation of Risk Factors Predicting Cataract Surgery Complications in Patients with Pseudoexfoliation Syndrome: A Systematic Review. J Clin Med. 2024;13(6):1824.
6. Palko J, Qi O, Sheybani A. Corneal alterations associated with pseudoexfoliation syndrome and glaucoma: A literature review. J Ophthalmic Vis Res. 2017;12(3):312–324.
7. Aoki T, Kitazawa K, Inatomi T, et al. Risk factors for corneal endothelial cell loss in patients with pseudoexfoliation syndrome. Sci Rep. 2020;10(1):7260.
8. Songur MS, Aslan S, Bayhan HA. Evaluation of the cornea endothelium by specular microscopy in pseudoexfoliation syndrome. Ahi Evran Medical Journal. 2021;5(3):202–206.
9. Bozkurt B, Güzel H, Kamış Ü, et al. Characteristics of the anterior segment biometry and corneal endothelium in eyes with pseudoexfoliation syndrome and senile cataract. Turk Oftalmol Derg. 2015;45(5):188–92.
10. Sofi DIA, Nawaz DS, Wani DJS. Central corneal thickness in eyes with pseudoexfoliation syndrome in Kashmir Valley - a hospital based study. International Journal of Medical Research and Review. 2015;3(9):934–8.
11. Sarowa S, Manoher J, Jain K, et al. Qualitative and quantitative changes of corneal endothelial cells and central corneal thickness in pseudoexfoliation syndrome and pseudoexfoliation glaucoma. Int J Med Sci Public Health. 2016;5(12):2526–2530.
12. Yüksel N, Emre E, Pirhan D. Evaluation of corneal microstructure in pseudoexfoliation syndrome and glaucoma: in vivo scanning laser confocal microscopic study. Curr Eye Res. 2016;41(1):34–40.
13. Tomaszewski BT, Zalewska R, Mariak Z. Evaluation of the endothelial cell density and the central corneal thickness in pseudoexfoliation syndrome and pseudoexfoliation glaucoma. J Ophthalmol. 2014;2014:1–7.
14. Akdemir MO, Kirgiz A, Ayar O, et al. The effect of pseudoexfoliation and pseudoexfoliation induced dry eye on central corneal thickness. Curr Eye Res. 2015;4:1–6.
15. Sato T. Cataract surgery in pseudoexfoliation syndrome using the eight-chop technique. J Pers Med. 2025;15(9):396.
16. Asfuroğlu Y, Karaca EE, Asfuroğlu M, et al. Predictive factors for long-term de novo intraocular pressure elevation after descemet membrane endothelial keratoplasty. Cornea. 2025.
17. Singh P, Sinha A, Nagpal R, et al. Descemet membrane endothelial keratoplasty: Update on preoperative considerations, surgical techniques, and outcomes. Indian J Ophthalmol. 2022;70(9):3222–3238.