A histomorphometric study of corneal endothelial cells in normal human fetuses

Corneal endothelial cell morphology in children with autosomal recessive Alport syndrome: a longitudinal study

PURPOSE

To evaluate the corneal endothelial cell morphology in children with autosomal recessive Alport syndrome (ARAS).

METHODS

This is a longitudinal, prospective cohort study that evaluated pediatric patients with genetically diagnosed ARAS. Fifty-eight eyes of 29 pediatric patients (12 patients, 17 controls) underwent a full ophthalmic examination. Corneal endothelial cell density (ECD) (cells/mm²), coefficient variation (CV) of cell area (polymegathism), the percentage of hexagonal cells (HEX) (pleomorphism), and central corneal thickness (CCT) were analyzed automatically using a noncontact specular microscopy.

RESULTS

The mean ECD was 2904 ± 355.48 cell/mm² in the ARAS group and 3263.20 ± 261.71 cell/mm² in the control group (p = 0.004). In the ARAS group, the mean CV was 46.53 ± 10.43, which was significantly higher than that in controls (p = 0.026). The mean HEX was 48.86 ± 14.71 in the ARAS group and 59.06 ± 10.64 in the control group (p = 0.038). The mean CCT was 565.26 ± 39.77 µm in the ARAS group and 579.66 ± 31.65 µm in the control group (p = 0.282). The comparison of endothelial cell characteristic of the ARAS group with 1-year follow-up is as follows: The mean ECD decreased from 2904 ± 355.48 cell/mm² to 2735 ± 241.58 cell/mm² (p = 0.003). The mean CV increased from 46.53 ± 10.43 to 47.93 ± 10.50 (p = 0.471). The mean HEX decreased from 48.86 ± 14.71 to 48.50 ± 10.06 (p = 0.916). The mean CCT decreased from 565.26 ± 39.77 µm to 542.86 ± 40.39 µm (p = 0.000).

CONCLUSION

Measurement of ECD and percentage of hexagonality can also be used as an indicator of the health of the corneal endothelium. In this study, the mean ECD and HEX were significantly lower in ARAS group than in age-matched pediatric controls. Polymegathism, which reflects cellular stress, was statistically significantly higher in ARAS group. The mean ECD and CCT decreased significantly at 1-year follow-up. This study may demostrated that endothelial damages and stress in ARAS patients appear in childhood and show a rapid increase with age.

Corneal Endothelial Features in Patients Operated for Primary Congenital Glaucoma

PURPOSE

To compare the corneal endothelial cell morphology using specular microscopy imaging between primary congenital glaucoma (PCG) and age-matched healthy controls, and to determine if the endothelial cell parameters vary among different subtypes of PCG.

DESIGN

Retrospective case-control study.

PARTICIPANTS

One hundred forty-five eyes of 145 patients operated for PCG between 1991 and 2018 and who returned for a follow-up visit between June 2021 and May 2022. Three hundred and nineteen age-matched healthy individuals constituted the control group.

METHODS

Corneal endothelial cell layer analysis was performed with EM-3000 (Tomey) noncontact specular microscope. Patients were categorized according to the clinical subtypes of PCG (neonatal, infantile, and late-onset) based on the Childhood Glaucoma Research Network classification.

MAIN OUTCOME MEASURES

Specular microscopic parameters, including endothelial cell density (ECD), average cell size, coefficient of variation (CV), and maximum and minimum cell size, were compared with that of the control group.

RESULTS

Mean ± standard deviation (SD) age of patients at endothelial imaging was 13.5 ± 6.54 years, and there was a male preponderance (n = 88, 61%). The majority of the patients had infantile-onset PCG (n = 67, 46%). Eyes with PCG demonstrated a significantly lower ECD compared with controls (2158.7 ± 636.5 vs. 2840.9 ± 232.5 cells/mm2; P < 0.0001). Other endothelial cell parameters were also significantly worse in PCG compared with controls. The mean ± SD ECD was 2344.3 ± 544.3, 2131.9 ± 626.4, and 2054.2 ± 714.0 cells/mm2 in neonatal onset, infantile, and late-onset PCG groups, respectively. Although the ECD was lowest in the late-onset PCG group, there was no significant difference in the ECD between the 3 subgroups. Except for CV, all the endothelial cell parameters were significantly worse in eyes with Haab striae than in eyes without.

CONCLUSIONS

Patients with PCG have significantly lower ECD compared with healthy controls. Furthermore, other endothelial cell parameters were also significantly worse in the PCG group. These changes in the corneal endothelium in patients with PCG should be considered in long-term medical and surgical management.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Refractive development I: Biometric changes during emmetropisation

PURPOSE

Although there are many reports on ocular growth, these data are often fragmented into separate parameters or for limited age ranges. This work intends to create an overview of normal eye growth (i.e., in absence of myopisation) for the period before birth until 18 years of age.

METHODS

The data for this analysis were taken from a search of six literature databases using keywords such as "[Parameter] & [age group]", with [Parameter] the ocular parameter under study and [age group] an indication of age. This yielded 34,409 references that, after screening of title, abstract and text, left 294 references with usable data. Where possible, additional parameters were calculated, such as the Bennett crystalline lens power, whole eye power and axial power.

RESULTS

There were 3422 average values for 17 parameters, calculated over a combined total of 679,398 individually measured or calculated values. The age-related change in refractive error was best fitted by a sum of four exponentials (r²  = 0.58), while all other biometric parameters could be fitted well by a sum of two exponentials and a linear term ('bi-exponential function'; r² range: 0.64-0.99). The first exponential of the bi-exponential fits typically reached 95% of its end value before 18 months, suggesting that these reached genetically pre-programmed passive growth. The second exponentials reached this point between 4 years of age for the anterior curvature and well past adulthood for most lenticular dimensions, suggesting that this part represents the active control underlying emmetropisation. The ocular components each have different growth rates, but growth rate changes occur simultaneously at first and then act independently after birth.

CONCLUSIONS

Most biometric parameters grow according to a bi-exponential pattern associated with passive and actively modulated eye growth. This may form an interesting reference to understand myopisation.

ASSESSMENT OF CORNEAL ENDOTHELIAL LAYER IN CONTACT LENS WEARERS WITH THE AID OF AN ENDOTHELIAL MICROSCOPE

AIMS

The main aim of our study was to demonstrate the difference in endothelial cell density between a group of keratoconus contact lens users and non-contact lens users (without keratoconus).

MATERIAL AND METHODS

In our study we had data from 96 subjects with an average age of 40.5 ±14.05 years. For the purposes of our study, we worked with each eye separately for each subject (n = 192). Keratoconus (research group) was diagnosed in 97 eyes. The mean age of the patients in the research group was 41.9 ±10.6 years. Keratoconus was not diagnosed in the remaining 95 eyes (control group). The mean age of the patients in the control group was 39.5 ±16.6 years. In the keratoconus group, the patients wore hard contact lenses (HCL) in a total of 43 eyes, hybrid contact lenses (HbCL) in 48 eyes and soft contact lenses (SCL) in 6 eyes. The average total period of contact lens use in the research group was 10.6 ±2.36 years.

RESULTS

The average number of endothelial cells in the research group was 2607.11 ±298.45 cells per mm2. The average number of endothelial cells in the control group was 2831.94 ±523.51 cells per mm2. We tested these two variables using a T-test, which showed a statistically significant difference (p &lt; 0.001). A statistically significant difference in the mean endothelial cell count related to patient age and use / non-use of contact lenses of two types was demonstrated only in the under-40 group in a comparison of the non-contact and keratoconus group with the keratoconus group using HCL (p = 0.02). A statistically significant difference in the length of contact lens wear was demonstrated between the keratoconus-free group with or without SCL and the keratoconus group when wearing HCL or HbCL for more than 20 years (p = 0.01 and p = 0.02). For HbCL users, this difference was demonstrated also after 15 years of wearing (p = 0.001).

CONCLUSION

From our results we can conclude that there is a difference in endothelial cell density between patients with and without keratoconus.

Corneal endothelial cell density and its correlation with birth weight, anthropometric parameters, and ocular biometric parameters in Chinese school children

Background

To describe the distribution of corneal endothelial cell density (ECD), and to explore its correlation with birth weight (BW), anthropometric parameters, and ocular biometric parameters in Chinese school children.

Methods

In the population-based cross-sectional Nanjing Eye Study, children were measured for anthropometric information, for ECD by the noncontact specular microscope and for ocular biometric parameters by the optic low-coherent reflectometer. Data from right eyes were analyzed to illustrate the distribution of ECD and for determining correlated factors with ECD using univariate and multiple linear regression analysis. Comparisons among three different BW groups were performed using a one-way ANOVA analysis followed by the Bonferroni correction for pairwise comparisons.

Results

Of 1171 children, the mean (± standard deviation) ECD was 2875.34 ± 195.00 cells/mm². In the Multiple Linear Regression analysis, BW, gender and central corneal thickness were significantly associated with ECD. The ECD increased by 36.16 cells/mm² with BW increasing by 1 kg (P = 0.001) and increased by 0.44 cells/mm² for every additional 1 mm in central corneal thickness (P = 0.01). The ECD of girls was 54.41 cells/mm² higher than boys (P < 0.001). Children born with low BW presented significantly lower ECD than those born with normal BW (P < 0.05) and high BW (P < 0.05). Age and axial length were not significantly associated with ECD (P = 0.06 and P = 0.21, respectively).

Conclusions

In Chinese school children aged 82 to 94 months, the ECD is positively correlated with BW and central corneal thickness, in which BW is a newly identified associated factor. It is like that gender plays an important role in ECD distribution while girls have relatively greater ECD than boys.

Corneal Endothelial Changes in Patients With Primary Congenital Glaucoma

PRCIS

Specular microscopic parameters were found to be decreased in patients with primary congenital glaucoma (PCG). Patients with PCG and Haab striae had lower endothelial cell density (ECD) and central corneal thickness (CCT) than those without Haab striae did. The type of surgery (viscogoniotomy, viscotrabeculotomy, or combined viscotrabeculotomy and trabeculectomy) did not affect specular microscopic parameters.

PURPOSE

The purpose of this study was to compare specular microscopic parameters such as corneal ECD, coefficient of variation (CV), hexagonal cell percentage (HEX), and CCT between patients with PCG and healthy controls; to determine the predictive ability of Haab striae for endothelial cell changes PCG by comparing patients with and without Haab striae; and to investigate if the type of surgery used to treat glaucoma (viscogoniotomy, viscotrabeculotomy, or combined viscotrabeculotomy and trabeculectomy) affects specular microscopic parameters.

METHODS

A cross-sectional specular microscopic analysis of patients with PCG and healthy controls was performed. One hundred eyes of 62 patients with PCG with and without Haab striae and 101 eyes of 101 healthy controls were enrolled in this study. Specular microscopic parameters, including ECD, HEX, CV, and CCT, of all subjects were evaluated.

RESULTS

Patients with PCG showed significantly lower ECD and CCT than healthy controls did. Those with Haab striae had lower ECD and CCT but no differences in age, HEX, and CV compared with those without Haab striae. ECD, CV, HEX, or CCT did not significantly differ among patients treated with the 3 different types of surgery.

CONCLUSIONS

Prolonged exposure to elevated intraocular pressure during prenatal and/or early postnatal life results in structural changes in immature infant corneas. Specular microscopic parameters differed significantly between healthy controls and patients with PCG. The type of surgery had no effect on these parameters. Among patients with PCG, those with Haab striae had isolated corneal endothelial cell loss without morphologic changes within the endothelium.

Phacoemulsification and IOL-Implantation without Using Viscoelastics: Combined Modeling of Thermo Fluid Dynamics, Clinical Outcomes, and Endothelial Cell Density

Phacoemulsification is a widely used surgical method in cataract surgery with a high energy ultrasound source. The viscoelastic is considered to be tissue protective. The aim of this study is to investigate during surgery the impact of using viscoelastic versus no viscoelastic on clinical outcomes, potential complications and effect on endothelial cell density. The study group included 64 patients, who were subjected to phacoemulsification using balanced salt solution (BSS). Control group consisted of 62 patients, who underwent phacoemulsification using Hyaloronic acid 1% Healon 1%. Student’s t-test was applied for statistical analysis. The simulations of temperature changes during phacoemulsification were performed by COMSOL Multiphysics software. In the BSS group, a mean endothelial cell loss (ECL) of 4.5% was measured one month postoperatively, while in the Healon group ECL was 5.3%. Data analysis showed no significant difference in ECL between the groups (Student’s t-test, p = 0.8). No significant difference was observed in endothelial cell morphology and IOP between the two groups pre- and postoperatively (all p > 0.05). The modeling of thermo fluid dynamics showed that the heating of the cornea is slightly less when Healon was used as irrigation fluid. The phacoemulsification technique can be performed by an experienced surgeon with viscoelastics or continuous anterior chamber (AC) irrigation on the same level of safety regarding endothelial cell damage, providing equally satisfying clinical outcomes.

Morphological features of the corneal endothelium in patients with pseudoexfoliative glaucoma

Purpose. To study the main morphological features of the corneal endothelium in patients with pseudoexfoliative glaucoma (PEG). Methods. We included 193 subjects aged from 55 to 75 years. The main study group (PEG) included 96 patients (192 eyes), the primary open angle glaucoma (POAG) group included 36 patients (72 eyes) with POAG, the PEX group included 31 patients (62 eyes) with pseudoexfoliation syndrome without glaucoma. The control group consisted of 30 healthy subjects (60 eyes). Main corneal endothelium parameters were evaluated using a non-contact endothelial microscope EM-935 (Haag Streit, Switzerland). Data were analyzed by STATISTICA 9 software for Windows. Results. The patients with PEG had lower endothelial cell density (ECD) in comparison to the control group (p < 0.01), and PEX group (p < 0.05). The polymegatism level in patients with PEG and POAG was higher than in the control group (p < 0.001, and p < 0.01, correspondingly). In patients with moderate and advanced PEG, the ECD was significantly lower (p < 0.01), and the polymegatism level was significantly higher (p < 0.01) than the same parameters in patients with early PEG. The lowest ECD and the highest polymegatism percentage were observed in PEG patients with more pronounced PEX manifestations, p < 0.05. No effect of IOP-lowering eye drops on the corneal endothelium parameters was revealed, p < 0.05. Conclusions. Significant morphological changes of the corneal endothelium (decreased endothelial cell density, increased polymegatism percentage) were revealed in patients with PEG. It was established that the severity of these changes is associated with the PEG and PEX severity. No effect of IOP-lowering eye drops on the corneal endothelium parameters was detected.

Riding the cell jamming boundary: Geometry, topology, and phase of human corneal endothelium

It is important to assess the viability of eye-banked corneas prior to transplantation due to inherent senescence and known loss of endothelial cells during surgical manipulation. Corneal endothelial cells have a complex basal and paracellular shape making them challenging to accurately measure, particularly in oedematous ex vivo tissue. This study used calibrated centroidal Voronoi Diagrams to segment cells in images of these human corneas, in order to characterize endothelial geometry, topology, and phase. Hexagonal cells dominated the endothelia, with most comprised of five different pleomorphs exhibiting self-similar topological coarsening through most of the endothelial cell density range. There was a linear relationship between cell size and shape, though cells with greater than six sides were present in larger proportions than cells with less. Hexagonal cell regularity was stable and largely independent of density. Cell and tissue phase was also examined, using the cell shape index relative to the recently discovered 'cell jamming' phase transition boundary. Images showed fluid endothelia with a range of shape indices spanning the boundary, independent of density but dependent on hexagonal regularity. The cells showed a bimodal distribution centred at the boundary, with the largest proportion of cells on the fluid side. A shoulder at the boundary suggested phase switching via shape transformation across the energy barrier, with cells either side having distinctly different size and shape characteristics. Regular hexagonal cells were closest to the boundary. This study showed the corneal endothelium acts as a glassy viscous foam characterized by well-established physical laws. Endothelial cell death transiently and locally increases cell fluidity, which is subsequently arrested by jamming of the pleomorphically diverse cell collective, via rearrangement and shape change of a small proportion of cells, which become locked in place by their neighbours thereby maintaining structural equilibrium with little energy expenditure.

Age-related changes of corneal endothelial cell in healthy Chinese tree shrew measured by non-contact specular microscope

AIM

To determine the impact of age on the morphology of endothelial cells and central corneal thickness (CCT) in Chinese tree shrew.

METHODS

One-hundred and twenty eyes of 60 healthy Chinese tree shrews were studied. Based on age, the tree shrews were divided into four groups. After general anesthesia, the images of endothelium were acquired using non-contact specular microscope Topcon 3000P. Eight parameters of corneal endothelial cells were measured by built-in software, including CCT, endothelial cell density (ECD), percent hexagonality (HG%), coefficient of variability (CV), size of minimal cell (Smin), size of maximal cell (Smax), average cells size (Savg) and size standard deviation (Ssd). Data were analyzed using STATA software. The differences of eight parameters among groups and correlations with age were analyzed.

RESULTS

In all studied animals, the average CCT was 249.6±20.29 µm (202-301 µm), ECD was 3080.72± 460.76 cells/mm² (1239.6-4047.6 cells/mm²) and CV was 29.10±7.60 (13.6-54.6). CV was significantly different among different groups (P<0.001). Strong correlation with age was found in ECD, Smax, Savg, Ssd and CV.

CONCLUSION

Cornea of Chinese tree shrews had half CCT of human cornea and similar ECD, CV and size of corneal endothelial cells. Young adult tree shrews had higher ECD, HG% and low CV. ECD, Smax, Savg, Ssd and CV correlated with age significantly.

Evaluation of corneal endothelial cell damage after vitreoretinal surgery: comparison of different endotamponades

PURPOSE

We evaluated corneal endothelial cell (EC) damage after vitreoretinal surgery and compared the results using different tamponades.

MATERIALS AND METHODS

This prospective controlled study included 45 eyes of 45 patients (24 females, 21 males) who underwent pars plana vitrectomy with gas (sulphur hexafluoride, SF6, 20%) or silicone oil (SO) tamponade. Patients were assigned to one of the three groups: group 1 (phakic, 20% SF6 gas), group 2 (pseudophakic, 20% SF6 gas), and group 3 (phakic, SO). Mean endothelial cell density (MCD), mean cell area (MCA), coefficient of variation in cell size (CV), and percentage of hexagonal cells (HC) values were measured using a non-contact specular microscope (SP-2000P; Topcon, Japan) at baseline and at 3 months after surgery. The fellow eye of each patient was used as a control.

RESULTS

Group 2, which had the lowest baseline MCD and MCA values, was found to be different than groups 1 and 3 (P=0.028 and 0.022, respectively). At 3 months postoperatively, all groups showed significantly lower MCD, HC and CV values than at baseline (all P<0.05). The mean changes in MCD at 3 months after surgery were 3.8±2.8% (mean±SD), 8.0±7.5%, and 4.6±5.4% in groups 1-3, respectively. The mean MCD changes in the fellow eyes were 0.31±1.41% in group 1, -0.63±1.90% in group 2, and 0.14±0.52 in group 3 at 3 months postoperatively (P>0.05 for all).

CONCLUSIONS

Our findings revealed that corneal EC damage may occur after vitreoretinal surgery with gas or SO tamponade. Eyes that had undergone previous cataract surgery were more vulnerable to EC loss than phakic eyes, supporting the protective effect of an intact lens.

Microarray analysis of cell cycle gene expression in adult human corneal endothelial cells

Corneal endothelial cells (ECs) form a monolayer that controls the hydration of the cornea and thus its transparency. Their almost nil proliferative status in humans is responsible, in several frequent diseases, for cell pool attrition that leads to irreversible corneal clouding. To screen for candidate genes involved in cell cycle arrest, we studied human ECs subjected to various environments thought to induce different proliferative profiles compared to ECs in vivo. Donor corneas (a few hours after death), organ-cultured (OC) corneas, in vitro confluent and non-confluent primary cultures, and an immortalized EC line were compared to healthy ECs retrieved in the first minutes of corneal grafts. Transcriptional profiles were compared using a cDNA array of 112 key genes of the cell cycle and analysed using Gene Ontology classification; cluster analysis and gene map presentation of the cell cycle regulation pathway were performed by GenMAPP. Results were validated using qRT-PCR on 11 selected genes. We found several transcripts of proteins implicated in cell cycle arrest and not previously reported in human ECs. Early G1-phase arrest effectors and multiple DNA damage-induced cell cycle arrest-associated transcripts were found in vivo and over-represented in OC and in vitro ECs. Though highly proliferative, immortalized ECs also exhibited overexpression of transcripts implicated in cell cycle arrest. These new effectors likely explain the stress-induced premature senescence that characterizes human adult ECs. They are potential targets for triggering and controlling EC proliferation with a view to increasing the cell pool of stored corneas or facilitating mass EC culture for bioengineered endothelial grafts.

Age-related changes in corneal thickness and endothelial characteristics

Purpose

To determine the influence of age on central corneal thickness (CCT), endothelial cell density (ECD), average cell size, coefficient of variation in cell size, and percentage of regular hexagonal cells; and to estimate the average ECD and CCT in seven age groups.

Materials and methods

After obtaining informed consent, 211 Caucasian patients (358 eyes) were examined using a noncontact specular microscope at the Center of Eye Diseases in Vilnius University Hospital Santariskiu Clinic. The main corneal parameters were: ECD, average cell size, coefficient of variation in cell size, percentage of regular hexagonal cells, and CCT. Subjects (20–89 years) were stratified by age into seven groups. Correlations between CCT, endothelial parameters (ECD, percentage of regular hexagonal cells, average, coefficient of variation), and age were found. Student’s t-test and Pearson’s correlation coefficient (r) values were calculated.

Results

A total of 114 (54.03%) women and 97 (45.97%) men participated in the study. Average ECD (cell/mm²) ranged from 2,931 (±371) in 20–29 year olds to 2,222 (±182) in 80–89 year olds; CCT (μm) ranged from 563 (±44) in 20–29 year olds to 540 (±35) in 80–89 year olds. A strong inverse correlation was observed between age and corneal ECD (r=−0.650, P<0.01) and a weak inverse correlation was observed between age and CCT (r=−0.156, P<0.01). ECD and CCT correlated directly (r=0.232, P<0.01). The average size of corneal endothelial cells directly correlated with age (r=0.586, P<0.01). There was no correlation between age and the coefficient of variation in cell size nor the percentage of regular hexagonal cells (P>0.05).

Conclusion

Young people have higher ECD. CCT also decreases, but its dependence on age is weaker. A lower cell density indicates a thinner cornea. The variation in cell size and percentage of regular hexagonal cells are not dependent on age.

Human ocular biometry

The aim of this study was to examine growth of the human eye globe and cornea from early in gestation to late in adult life. Globe antero-posterior length, horizontal and vertical diameters, corneal horizontal and vertical (white to white) diameters and posterior pole to limbus distances were measured using digital calipers (±0.01 mm) in 541 postmortem eyes. Additional pre- and postnatal data for some of the dimensions were obtained from the literature. All dimensions examined increase rapidly during prenatal development but postnatal growth differs. Growth of globe antero-posterior length, vertical and horizontal diameters as well as corneal vertical and horizontal diameters stops within 1 year after birth. Logistic analysis is consistent with an asymptotic prenatal growth mode and no further growth after its completion around 1 year after birth. Horizontal and vertical globe diameters are the same at all ages but the corneal horizontal diameter is always larger than the vertical diameter. No differences could be detected between males and females in any of the ocular dimensions. Globe and corneal growth take place primarily during the prenatal growth mode and dimensions reach their maxima, shortly after birth. It is suggested that cessation of a growth stimulating signal at birth marks the end of the prenatal growth mode and that the small increases over the next year are due to cells already stimulated. Male and female eyes of the same age have the same globe and cornea dimensions.

Fuchs' corneal dystrophy

Fuchs' corneal dystrophy (FCD) is a progressive, hereditary disease of the cornea first described a century ago by the Austrian ophthalmologist Ernst Fuchs. Patients often present in the fifth to sixth decade of life with blurry morning vision that increases in duration as the disease progresses. Primarily a condition of the posterior cornea, characteristic features include the formation of focal excrescences of Descemet membrane termed 'guttae', loss of endothelial cell density and end-stage disease manifested by corneal edema and the formation of epithelial bullae. Recent advances in our understanding of the genetic and pathophysiological mechanisms of the disease, as well as the application of new imaging modalities and less invasive surgical procedures, present new opportunities for improved outcomes among patients with FCD.

Growth of the cornea from infancy to adolescence

The intraocular distance and iris diameter of children and young adolescents were measured, with the aid of a measuring microscope, from photographs of their faces. True intraocular distance was measured with an intraocular caliper at the same time that the photographs were taken. These data were then compiled and horizontal visible iris diameters (HVIDs) were calculated. An equation was derived from the optics of the Gullstrand model eye to calculate horizontal corneal diameter (HCD) from HVID. Comparisons of HVIDs revealed no significant correlation with age in either a regression plot of cross-sectional data for subjects aged 1 month to 1 year, or all subjects whose ages ranged from 1 month to adolescence. Additional longitudinal data for 13 individuals, who had been photographed as both an infant (mean = 3.4 months) and as an older child or adolescent (mean = 8.6 years), were then compiled and HVIDs for these subjects at two different ages were compared. A Wilcoxon signed rank test revealed a small but significant amount of growth, 0.318 mm (p-value = 0.013), in the HVIDs over a mean age difference of 8.3 years for individuals measured twice during their lifetimes. The regression equation for this growth was: HVID = 10.52 (+/-0.095 S.E.) + 0.0305 (+/-0.014) x Age (years). From a comparison of data from earlier literature and our own measurements, we conclude that, after birth, the fastest growth of the cornea must occur during the first few months of life.

Assessments of corneal endothelial cell density in growing children and its relationship to horizontal corneal diameter

BACKGROUND

Few studies have been published of corneal endothelial cell density (ECD) in children, especially in relation to the age and corneal size of the individuals. The possible effect of corneal enlargement on the endothelium was studied, and the results were objectively reviewed in relation to literature reports on corneal diameter and age.

METHODS

ECD was assessed in 119 children aged 5 to 15 years after endothelial photography with a noncontact specular microscope (Topcon SP-1000 or SP-2000P), followed by manual digitization of cell overlays. The horizontal corneal diameter, as the visible iris diameter, was measured to 0.5-mm accuracy.

RESULTS

The mean +/- SD value for ECD, calculated using all individual cell area values, was 3542 +/- 510 cells/mm2 (range, 2576 to 5316), whereas it was 3246 +/- 416 cells/mm2 (range, 2404 to 4817) if the mean cell area value from each image was used to calculate ECD. The mean horizontal corneal diameter was 11.48 +/- 0.58 mm (+/- SD). The corneal diameter was not obviously age-related for this group, but there were clear trends for younger children to have higher ECD values than older children (p2, depending on the method for calculating ECD.

CONCLUSIONS

ECD values were found to be significantly correlated to corneal diameter in children aged 5 to 15 years, and this factor should be considered in comparative studies.