Original Article

Evaluating the change in central corneal thickness in neonates

(term and preterm) in Indian population and the factors affecting it

Jitendra Jethani, Kalpit Shah1, Monika Jethani2

Background and Aim: Central corneal thickness (CCT) of term and preterm infants in Indian population is Access this article online
not known. We did a prospective noninterventional study to measure the CCT in term and preterm infants. Website:
Materials and Methods: An ultrasonic pachymeter was used. The data regarding the date of birth, expected www.ijo.in
date of delivery, birth weight were recorded. The preterm and the term infants were followed up at 8 weeks, DOI:
20 weeks and at 1‑year. Results: A total of 85 (170 eyes) children were included in the study. The mean 10.4103/0301-4738.162601
age was 264.6 ± 21.8 days postconception. The mean birth weight and CCT were 1834.4 ± 512.1 g and 595.8 PMID:
*****
± 72.4 μ respectively. A comparison of CCT on the basis postgestational age showed a mean thickness of
Quick Response Code:
620.7 ± 88.8 and 574.4 ± 78.3 μ in the <260 days and >260 days age groups respectively. The difference was
statistically significant (Student’s test, P = 0.002). The CCT of preterm infants (<260 days) decreased from a
mean value of 620.7 ± 88.8 μ to 534.1 ± 57.6 μ at the end of 1‑year. Conclusion: We present the data of CCT
in term and preterm infants in Indian population. We believe that the premature babies have slightly thicker
corneas than mature term babies.

Key words: Central corneal thickness, preterm infants, term infants

Central corneal thickness (CCT) has become an important readings were excluded. The rest of three readings were averaged
parameter for diagnosis and treatment of various eye and included. No speculum was used during the measurement
disorders. More and more children are now born at very of the data. The data regarding date of birth expected date of
low gestational age. There is very scant data on the CCT of delivery and birth weight were recorded. For the purpose of
premature and full‑term children during the neonatal period. comparison, we took a postconceptional age (PCA) only. The
Autzen and Bjørnstrøm[1] (13 premature infants), Kirwan et al.[2] PCA of each infant was determined based on obstetric history,
(35 premature infants) and more recently by De Silva et al.[3] early obstetric ultrasound and confirmed by clinical examination
(56 premature infants), Uva et al.[4] (33 premature infants) and of the newborn infant. Similar to other studies reported in the
Gunay et al.[5] (100 premature infants) have presented their literature, exclusion criteria were retinopathy of prematurity
findings on the CCT in premature children. We, therefore, Stage II or higher and neurological or syndromic diseases. None
decided to do a prospective noninterventional study to measure of the patients on gross examination seems to have corneal
the CCT in preterm and term infants in Indian population. dystrophy. Any cases of trauma to cornea/lid or other structures
This is to the best of our knowledge the first study in Indian were excluded. Ocular abnormalities such as corneal and iris
population and the only study, which has followed up the same alterations, congenital cataract, retinopathy and glaucomatous
set of neonates for the measurement of CCT. optic disc changes (CD >0.4) were excluded. Patients with factors
possibly affecting intraocular pressure (mechanical ventilation
Materials and Methods or pulmonary or circulatory complications) also were excluded.
A total of 85 (170 eyes) children were included in the study. The None of the parents had a history of consanguinity. Any
study was done at Krishna Children Critical Care, Vadodara baby with a history of forceps delivery or trauma to any ocular
and Synergy NICU, Ahmedabad. Who underwent retinopathy structure was excluded from the study. The preterm and term
of prematurity screening program and all examinations were infants were followed up at 8 weeks, 20 weeks and at 1‑year
performed within first 2 days of birth. Informed consent was
and CCT were measured on all follow‑up visits. Only children
obtained from the parents. An ultrasonic pachymeter (300 AP +
who came to us for the 1‑year follow‑up were included.
Pacscan Plus, Sonomed Escalon, Stoneham, MA, USA) used to
measure the CCT for both the eyes of all the neonates. Topical Results
anesthesia was achieved by proparacaine eye drops. A total of
5 readings were taken for each eye and the lower and higher A total of 85 infants (170 eyes) with 43 term infants (86 eyes)
and 42 preterm infants (84 eyes) were included in the study.
Mean CCT was 595.8 ± 72.4 μ in 170 eyes. For the purpose of
Pediatric Ophthalmology, Baroda Children Eye Care and
Squint Clinic, 2Refractive Surgery, Eye Q Hospitals, Vadodara,
calculation, the age at which CCT was measured was divided
1
Pedaitric Ophthalmology and Squint Clinic, M and J Western Regional on the basis of PCA of more than and less than and equal to
Institute of Ophthalmology, Ahmedabad, Gujarat, India 260 days postconception.
Correspondence to: Dr. Jitendra Jethani, Baroda Children Eye Care The mean age of the children in ≤260 days, PCA was 242.4 ±
and Squint Clinic, 101, Sunrise Apartment, 4, Nutan Bharat Society, 15.1 days and in the >260 days PCA group was 278.9 ± 9.1 days.
Alkapuri, Vadodara, Gujarat, India. E‑mail: xethani@rediffmail.com The mean birth weight was 1410.5 ± 305.2 g and 2105.1 ± 498.8 g
Manuscript received: 20.07.14; Revision accepted: 27.05.15 in the ≤260 days PCA and >260 days PCA groups respectively.
502 Indian Journal of Ophthalmology Vol. 63 No. 6

The P = 0.00002 was highly significant. The mean CCT in the 574.4 ± 78.3 μ for term infants. Ehlers et al.[9] noted that there
≤260 days PCA and >260 days PCA was 620.7 ± 88.8 and 574.4 is a small further reduction in the CCT and reaches the value
± 78.3 μ respectively. The P value was 0.002 (Student’s t‑test) of the adult cornea at the age of 3 years.[9] CCT values of
and was highly significant. premature infants at a PCA of 40 weeks are therefore similar
to those obtained in newborns of 40 weeks of gestation. De
The comparison of CCT was also done on the basis of weight Silva et al.[3] reported a CCT of 546 ± 12 μ at 40 weeks PCA
of the baby (not the birth weight) at the time of examination. whereas Uva et al.[4] reported a CCT of 576 ± 26 μ in full‑term
The infants (term and preterm) were divided in three groups newborns. Our data of 574.4 ± 78.3 μ are very similar to Uva
<1500 g, 1500–2000 g and >2000 g; the mean CCT was 610.3 et al.[4] and is in complete agreement with the majority of
± 88.4, 599.6 ± 93.4 and 578.4 ± 71.8 μ respectively in the studies[7,8,10] [Table 2] except for the study by De Silva et al.[3]
three groups. The P value was not significant on inter‑group The reduction in the corneal thickness started within first few
comparison ANOVA though it seems that the higher birth weeks in our study. The children in our study had a slightly
weight had thinner central corneas. higher thickness even at the end of 1‑year compared to the
The CCT of preterm infants remained higher compared to term infants.
term infants but was not statistically significant. The CCT of Birth weight was analyzed by Uva et al. [4] and on
preterm infants (<260 days) decreased from the mean value of multivariate analysis they found a significant correlation of
620.7 ± 88.8 μ to 578.3 ± 79.6 μ at the end of 8 weeks. At the end CCT with birth weight. Gunay et al.[5] also correlated birth
of 20 weeks, it was 558.4 ± 52.4 μ which further reduced to 534.1 weight and CCT. His study on premature children suggested
± 57.6 μ at the end of 1‑year. The CCT of the infants (>260 days that the birth weight was negatively correlated with CCT.
postconception) decreased from 574.4 μ to 556.6 μ (8 weeks), Though in our study it was obvious that birth weight would
544.6 μ (20 weeks) and 530.2 μ (1‑year) [Fig. 1]. be an important factor, we believe that since birth weight was
significantly lower in the premature infants, a correlation
Discussion of thicker corneas with lower birth weight was likely and
Autzen and Bjørnstrøm[1] reported CCT values of 656 ± 103 μ at 5 therefore we took into consideration the actual weight at
days of life, 654 ± 84 μ at 20 days and 566 ± 64 μ at 110 days. They the time of examination (not the birth weight) and found no
found no difference in CCT at the first and third postnatal week significant difference. It could have still been possible that all
and that at the age of 3 months the thickness decreases to the low birth weight babies were premature ones as their weights
same level of the full‑term newborns. No correlation was found would have improved at a slower rate compared to the term
between gestational age and CCT. However, Kirwan et al.[2] infants. However, the data does suggest that an infant with
lower weight has a thicker cornea.
studied 35 premature infants (70 eyes), born at a gestational
age ranging from 23 to 32 weeks, in four PCA groups: 30–32, This reduction in cornea thickness has been correlated with
34–35, 37–38, and 39–41 weeks. At these ages, CCT was 691 ± 87, the increased transparency of the infant corneas secondary
648 ± 72, 605 ± 59 and 564 ± 34 μ, respectively. De Silva et al.[3] to evaporation, corneal remodeling as they grow. [4] The
(n = 56) showed a gradual decrease in the CCT from 794 ± 34 experimental evidence that the corneal hydration is the cause
μ at 28 weeks PCA to 559 ± 13 μ at 42 weeks PCA. Uva et al.[4] for the reduced transparency has also been linked with the
reported a mean CCT of 599 ± 36 μ in premature newborns (n = increased thickness of the cornea in younger infants.[3] Since
33). Our data of 620.7 ± 88.8 μ for children for preterm children we did not measure other ocular parameters of the eye, we
is similar to reported by Uva et al.[4] but lower than the studies cannot attribute the reason for thinning of the cornea to the
by Autzen and Bjørnstrøm,[1] Kirwan et al.,[2] De Silva et al.[3] reduction of corneal edema, it could be because of increase
and Gunay et al.[5] in corneal diameter. This would, however, require further
studies in the light of present finding that the cornea is thin
Studies on full‑term newborns at birth found CCTs ranging in older neonates.
from 573 to 585 μ [Table 1].[6‑8] Our study shows a CCT of
Conclusion
Table 1: Mean central corneal thickness in preterm and Central corneal thickness is higher in the preterm infants
term infants (related to PCA and weight) than in the term infants in Indian
At birth At 8 weeks At 20 weeks At 1-year population. The lower birth weight seems to be an independent
(microns) (microns) (microns) (microns) factor for CCT. The corneal thickness reduces with age and is
almost similar to term infants by 20 weeks of age. The values
Preterm 620.7±88.8 578.3±79.6 558.4±52.4 534.1±57.6 should be kept in mind while dealing with corneal problems
Term 574.4±78.3 556.6±68.1 544.6±55.6 530.2±60.3 in preterm and term infants in Indian population.

Table 2: Comparison of previous studies and our data on central corneal thickness in preterm and term infants
Autzen Kirwan De Silva Uva et al. Autzen Portellinha Remón Gunay et Muslubas Our study
et al. (1991) et al. et al. (2011) et al. et al. et al. al. (2013) et al.[10] (2014) (2014)
(2005) (2011) (1989) (1991) (1992)
Preterm 656±103 691±87 794±34 599±36 647.79±63.9 600±50 620.7±88.8
infants
Term 546±12 576±26 581±47 573±52 585±52 586±48 574.4±78.3
infants
 Jethani, et al.: Central corneal thickness in infants
June 2015 503

2. Kirwan C, O’Keefe M, Fitzsimon S. Central corneal thickness and

corneal diameter in premature infants. Acta Ophthalmol Scand
2005;83:751‑3.
3. De Silva S, Parentin F, Michieletto P, Pensiero S. Corneal curvature
and thickness development in premature infants. J Pediatr
Ophthalmol Strabismus 2011;48:25‑9.
4. Uva MG, Reibaldi M, Longo A, Avitabile T, Gagliano C, Scollo D, et
al. Intraocular pressure and central corneal thickness in premature
and full‑term newborns. J AAPOS 2011;15:367‑9.
5. Gunay M, Celik G, Gunay BO, Dogru M, Gursoy T, Ovali HF.
Central corneal thickness measurements in premature infants. Int
J Ophthalmol 2014;7:496‑500.
6. Autzen T, Bjørnstrøm L. Central corneal thickness in full‑term
newborns. Acta Ophthalmol (Copenh) 1989;67:719‑20.
7. Portellinha W, Belfort R Jr. Central and peripheral corneal thickness
in newborns. Acta Ophthalmol (Copenh) 1991;69:247‑50.
8. Remón L, Cristóbal JA, Castillo J, Palomar T, Palomar A, Pérez J.
Figure 1: The comparison of central corneal thickness in term and Central and peripheral corneal thickness in full‑term newborns by
preterm infants and the gradual reduction in the thickness of cornea ultrasonic pachymetry. Invest Ophthalmol Vis Sci 1992;33:3080‑3.
over a period of 1-year 9. Ehlers N, Sorensen T, Bramsen T, Poulsen EH. Central corneal
thickness in newborns and children. Acta Ophthalmol (Copenh)
1976;54:285‑90.
Acknowledgment
10. Muslubas IB, Oral AY, Cabi C, Caliskan S. Assessment of the
The authors thank Krishna Children Critical Care, Vadodara, central corneal thickness and intraocular pressure in premature
Synergy children critical care, Ahmedabad and NICU, Civil hospital, and full‑term newborns. Indian J Ophthalmol 2014;62:561‑4.
Ahmedabad for their cooperation and support.
Cite this article as: Jethani J, Shah K, Jethani M. Evaluating the change in
References central corneal thickness in neonates (term and preterm) in Indian population
and the factors affecting it. Indian J Ophthalmol 2015;63:501-3.
1. Autzen T, Bjørnstrøm L. Central corneal thickness in premature
Source of Support: Nil. Conflict of Interest: None declared.
babies. Acta Ophthalmol (Copenh) 1991;69:251‑2.