PEX typically affects several structures of the anterior segment of the eye, however there is lack of consistent evidence on PEX incidence and prevalence . PEX prevalence is published to be 0.2–30.0% with increasing prevalence with increasing age around the World. The differences in geographical, ethnic and race features, as well as age and gender distributions of the study participants and methods of diagnosing PEX [2, 4, 9, 18, 19]. Dissemination of PEX varies in different studies: 1.8% in USA , 2.3% in west Sydney Australia , 3.4% in India , 5.7% in Turkey , 16,1% in Greece , 16.3% in Australia (Aborigines), 16.9% in Middle Norway, 18.0% in Middle Sweden, 22.1% in Finland, Oulu , 39.3% in Ethiopia .
In Lithuania, PEX prevalence was found to be 43.9%, in 76–83 age group, as high as in Iceland (40.6% in those of 80 years old).
Prevalence of PEX increased with age in all studies [6, 9, 10, 19, 23–26]., this is in agreement with our finding as well and those with PEX are older than those without (72.2 ± 8.1 yrs vs 68.6 ± 8.2 yrs, respectively). Similarly, in Turkey the highest PEX rate was in the 80 years old patients (18.4%) with an increased odds ratio of 45.78 (p < 0.01) when compared to the 40–49 age-group . A previous Lithuanian study  found that PEX risk increases by 13.5% with every year of age increase. A Swedish study agrees with the age dependent increase, and established the annual incidence of PEX being 1.8% (95% CI 1.3–2.4). Thessaloniki longitudinal, population-based study found the 12-year incidence of PEX was 19.6% (95% CI, 17.1–22.2). Icelandic study found that on average there was a 5% increase in risk of developing definite PEX for every decade people older than 50 years (OR = 1.05; 95% CI 1.01–1.09, p = 0.022).
Conversely, there are limited data on the incidence of PEX and on factors associated with the development of PEX . This is mainly because few population-based studies in the field of glaucoma and even fewer studies in the field of PEX have re-examined their initial population to collect longitudinal data : The Reykjavik Eye Study (5-year and 12-year follow-up)[6, 29]; the study by Aström and co-workers  in Skelleftea, Northern Sweden (21-year follow-up); the Chennai Eye Disease Incidence Study (6-year follow-up) and The Thessaloniki longitudinal, population-based study in Northern Greece (12-year follow-up) are the only prospective longitudinal population- based studies to have provided incidence data for PEX . We couldn’t find any follow-up study about prevalence of PEX held in Baltic countries. There are three Baltic states: Lithuania, Latvia and Estonia. Lithuania is situated on the eastern shore of the Baltic Sea in Northern Europe. The prevalence of PEX in Lithuania was found (34.2%) as high as in Iceland (40.6% in those of 80 years old). There is data from Estonian researches 2004 y, the prevalence of PEX − 35.4%  and 2010 y, the prevalence of PEX − 25.5% . The prevalence of PEX in Latvia is 21.6% . The highest prevalence rates of PEX is described in Nordic countries [3, 4]. It was interesting to explore Lithuania’s population, whether PEX prevalence is as high as in other Northern countries.
It is established progression of PEX from unilateral to bilateral with aging . In Icelandic study 71.0% of clinically unilateral PEX cases had converted to bilateral over 12 years . In Sweden study 55.0% of unilateral converted to bilateral PEX during 21 years follow-up . In our follow-up study 53.0% of unilateral PEX had progressed to bilateral PEX in 10 years period.
Several studies reported that prevalence of PEX in female is higher than in male [3, 6, 7, 24]. Conversely, Kiliç found a significant relationship between PEX and male gender [10, 32]. In our study, PEX was more common in male 45.6% than in female 42.9%, but the difference between gender groups was not statistically significant. Other studies found no association of PEX with sex [23, 33, 34].
In Saudi Arabian study no significant relation was found between education level, occupation and life style of the patients and prevalence of PEX . In our study secondary education for men showed tendency for bigger risk of having PEX. The probability of having PEX for men reduced by adjusting by risk factors: alcohol consumption 1–4 time/month and alcohol consumption > 1 time/week, marital status-married, former and current smokers, normal weight, but not significantly. Adjusting by multivariate risk factors, secondary and university education, normal weight and overweight reduced the probability of having the PEX for women, but not significantly.
The Reykjavik Eye Study initially explored potential risk factors for the prevalence of PEX: older age, female sex, increased iris pigmentation, moderate use of alcohol, and asthma were associated with higher prevalence of PEX; the consumption of vegetables and fruit was associated with lower prevalence of PEX. When the same variables the consumption of vegetables and fruit was associated with lower prevalence of PEX . When the same variables were included in a risk factor analysis on the 5-year incidence of PEX, significant associations were found only with age and the consumption of fruit . However, in the risk factor analysis for the 12-year incidence of PEX, there were no statistically significant associations . Being married was shown to be protective for definite PEX in a univariate analysis. However, controlling for the effect of age eliminated this association [7, 27].
In the Thessaloniki Eye Study sex, smoking, alcohol consumption, BMI, CCT didn’t show statistical significance .
In the Chennai Eye Disease Incidence Study older age, rural residence, illiteracy, pseudophakia and nuclear cataract were significantly associated with the 6-year incidence of PEX [27, 30].
In our study secondary education for men shows tendency for bigger risk of having PEX. Adjusting by multivariate risk factors without excluding gender, former and current smokers, normal weight showed tendency to reduce the probability of having the PEX, but not significantly.
Radius of CC was found to be age-independent and significantly steeper in females than in males . In our study we confirmed that females’ CC radius was significantly steeper than for males (7.6 vs 7.8 mm; p < 0.001), and that the the cornea became flatter during the 10-years of follow-up (7.6 vs 7.7 mm; p < 0.001). Hepsen et al. reported significantly steeper corneal curvature in PEX eyes compared to those without . We couldn’t confirm this tendency in our study which is in agreement with another study on this issue .
CCT appears to be independent of age and gender.  and while our findings for gender was the same, we did find that that CCT became significantly thinner with aging (p < 0.001).. Some studies claim that in PEX, CCT values are significantly lower than those in non-PEX eyes [39, 40]. We agree with authors that CCT is smaller in PEX group comparing with no-PEX (p < 0.006). On the contrary, Krysik found CCT thicker in PEX group . Many authors report that there is no significant difference in CCT between PEX and no-PEX groups [7, 37, 38, 42–45].
Lens opacification occurs in a high proportion of eyes with PEX and so PEX patients commonly require surgical intervention for their cataract  (most commonly nuclear).
Nuclear sclerosis predominated in eyes with PEX compared to those without PEX (57.6% and 36.9%, respectively), confirmed by the findings of the Blue Mountains Eye Study where after 10 years follow-up, eyes with PEX had a significantly greater prevalence nuclear cataract after adjusting for relevant factors (OR = 1.90; 95% CI, 1.04–3.48). In contrast, while we found a large number of nuclear cataract both in PEX and no-PEX groups, we could not confirm difference in our population. On the contrary, Gunes found that mixed cataract was the most common cataract type in the PEX patients in Turkey . In 30-years follow-up study Ekström and colleague found that PEX was the second most important predictor for cataract surgery after lens opacities, accounting for a 2.38-fold increased risk, male had a lower risk for cataract formation . In our follow-up study in PEX group showed tendency to have higher risk 1.2% to have cataract (95% CI 0.576–2.574; p = 0.61).
In a Turkish population, the prevalence of age-related macular degeneration was found to be significantly higher in PEX group than in those with no-PEX (17.9% vs 9.5%, p = 0.03), but in our study we couldn’t confirm this tendency.