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International Journal of Biological & Medical Research

Int J Biol Med Res. 2014; 5(4): 4495-4498

Intraocular Pressure In Different Trimesters Of Pregnancy

Sugapriya .G.,Yamini .D.S,,Thamaraiselvi,.Ramachandran.C

Department of physiology, ESICmedical college & PGIMSR,KK Nagar,Chennai, SRM medical college ,kattankulathur

A R T I C L E I N F O A B S T R A C T

Keywords:Intraocular pressureSchiotz tonometerPregnancy

Original Article

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INTRODUCTION

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The period of pregnancy is frequently accompanied by eye

manifestations of a disturbing nature in women who appear to be

normal in all other aspects. (Mishra Vet al., 2012) The normal

reproductive years of the female are characterized by monthly

rhythmical changes in the rates of secretion of the female hormones

and the corresponding physical changes in the ovaries and other

sexual organs.

. Pregnancy is the physiological phenomenon beginning with

fertilization and ending at birth. Pregnancy is divided in to three

periods called trimester. Each trimester is about 3months

duration.. Pregnant women undergo a tremendous number of

changes both systemic and ocular throughout the pregnancy.

Earlier studies have concentrated more on last trimester of

pregnancy Here we have focused on all the three trimesters of

pregnancy and the changes in intraocular pressure is noted

meticulously.

AIM and OBJECTIVE

This study was done to observe and analyze changes in

intraocular pressure during pregnancy ..

INTRAOCULAR PRESSURE

The intraocular pressure refers to the pressure exerted by

intraocular fluids on the coats of the eyeball. The normal

intraocular pressure varies between 10 and 21mmHg. The normal

level of IOP is essentially maintained by a dynamic equilibrium

between the formation and outflow of the aqueous humour.

Aqueous humour, a clear liquid that nourishes the cornea and lens

is produced in the ciliary body by diffusion and active transport

from plasma. It flows through the pupil and fills the anterior

chamber of the eye. It is normally reabsorbed through a network of

trabeculae into the canal of schlemm, a venous channel at the

junction between the iris and cornea. Obstruction of this outlet

leads to increased intraocular pressure.

THE EFFECT OF PREGNANCY ON IOP:

HORMONAL CHANGES DURING PREGNANCY

In pregnancy, the placenta forms large quantities of human

chorionic gonadotropin (HCG), estrogen, progesterone and human

chorionic somatomammotropin, which are essential for a normal

pregnancy.

ESTROGEN AND PROGESTERONE:

The placenta like the corpus luteum, secretes both estrogens

and progesterone, these are secreted by the syncitial trophoblast

cells of placenta. Throughout the pregnancy, estrogen levels

gradually rises and reaches a peak at 40 weeks, towards the end of

pregnancy. The daily production of placental estrogen increases to

about 30 times the mother's normal level of production.

Aim and objective:It was reported that intraocular pressure changes in different trimesters of pregnancy .This study was done to analyse the changes in intraocular pressure and correlated the finding ..Methods:In this study we analysed 50 pregnant women of different trimesters.Women with refractive errors and with cardiovascular or endocrine diseases were excluded from the study.After ethical clearance and consent from the participants,intraocular pressure was measured using Schiotz tonometer.We analysed the results statistically using analysis of variance method.Results:.In pregnant women,IOP increased during the first trimester and decreased in advanced pregnancy.Conclusion: This present study suggests that there is a change in intraocular pressure during the third trimester of pregnancy but not in first or second trimester due to hormonal variations associated with each condition.

* Corresponding Author : Sugapriya

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Sugapriya .G et al. Int J Biol Med Res. 2014; 5(4): 4495-4498

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Progesterone is secreted in moderate quantities by the corpus

luteum at the beginning of pregnancy, later it is secreted in

tremendous quantity by the placenta, averaging about 10 fold

increases during the course of pregnancy. But occasionally the

progesterone levels falls at 38 weeks but this is not constant.

HUMAN CHORIONIC GONADOTROPIN:

With the development of trophoblast cells from the early

fertilized ovum, the hormone HCG is secreted by the syncitial cells in

to the fluids of mother .the secretion of this hormone can be

measured first in the blood 8 to 9 days after ovulation , shortly after

the blastocyst implants in the endometrium. Then the rate of

secretion rises rapidly to reach a maximum at about 10-12 weeks of

pregnancy and decreases back to a lower value by 16 to 20 weeks. It

continues at this level for the reminder of pregnancy.

* Brachial blood pressure measurements were taken in supine

posture with calibrated sphygmomanometer.

* Body weight was recorded using weighing machine

* IOP was recorded by using Schiotz tonometer.

SCHIOTZ TONOMETER:

It is an indentation tonometer which was devised by Schiotz in

the year 1905.

TECHNIQUE OF SCHIOTZ TONOMETER

Before use, the Schiotz tonometer has to be placed up on the

converse test block given. The pointer should be on zero. If the

Pointer has another position, the instrument requires

readjustment. For measuring the tension, the patient is laid in the

recumbent position and the cornea is anaesthetized with 3 drops of

Lignocaine. Subject is instructed to look straight upwards (fixed

object).Then the lids are retracted gently with left hand without

exerting pressure on the eye ball. Then the foot plate of the

tonometer is gently placed vertically on the centre by holding the

handle of the tonometer in lowered to a position midway between

the top and foot plate of the cylinder, there by the instrument will act

independently by its own weight. The reading on the scale is

recorded as soon as the needle becomes steady.

The scale of Schiotz tonometer is calibrated in such a fashion

that each scale unit represents 0.05 mm protrusion of the plunger.

the recording of the IOP should always be started with 5.5 gms

weight . However, if the scale reading is less than 1, additional

weight should be added to the plunger to make it 7.5gm or 10gm as

indicated. A conversion table or Friedenwald nomogram is then

used to derive the IOP in mm Hg from the scale reading and the

plunger weight.

PROCEDURE:

Before performing the procedure the hands should be washed

and kept dry. Add two drops of local anesthetic and wait for 30

seconds. Ask the patient to look at a fix object and to keep absolutely

still.

With the thumb and the index finger of one hand, gently hold

open the patients eyelid taking care not to put any pressure on the

eyes. With the other, hold the tonometer between the thumb and

index finger and place the plunger on the central corneal surface

and note the scale reading. Then clean and dry the tonometer ahead.

Repeat the procedure for the other eye also. IOP is very much

influenced by corneal thickness and rigidity as already stated .

Conversion Table (from 1955 revision): Assumes Average

Ocular Rigidity (PO in mmHg)

MATERIALS & METHODS

· Schiotz tonometer, Weights and scale card, Local Anaesthesia

(lignocaine), Anti inflammatory drops (paracaine), Clean cotton of

gauze swab.

In this study, 50 pregnant women were studied. The study

population was divided in to three groups;

Group I first trimester, Group II: second trimester , Group

III:third trimester

Informed consent was taken from the volunteers to measure

the intraocular pressure. Intraocular pressure was measured using

Schiotz Tonometer . Before starting the study, the protocol was

approved by the Ethical Clearance Committee.

The study population was selected based on the following criteria

INCLUSION CRITERIA:

· Individuals between the age of 18-60 years were included in

this study.

· 50 Normal pregnant women in first ,second and third trimester.

EXCLUSION CRITERIA:

* Subjects with refractive errors

* Subjects with irregular menstrual cycle

* Subjects with cardiac or respiratory diseases

* Subjects with any pre-existing endocrinal disorders

METHODOLOGY:

Before recording IOP the following parameters were recorded

like age, weight, body mass index, blood pressure, social status

using appropriate standard instruments.

Table 1: INTRAOCULAR PRESSURE IN DIFFERENT TRIMESTERS

OF PREGNANCY

DISCUSSION

Results suggests that a hormonal influence may be acting in the

female to protect the outflow channels of the anterior chamber .A

more likely state of affairs would seem that a balance is maintained

by the three hormones working together, oestrogen and

progesterone providing a back ground against which relaxin can

take effect In Our study we found that there was a significant

decrease in IOP in advanced pregnancy

There are many mechanisms that have been proposed to

explain why IOP decreases during pregnancy in healthy women.

Initial theories focused on the hormonal levels that fluctuate during

pregnancy, such as oestrogen, relaxin, progesterone, and β- human

chorionic gonadotropin. It has been shown that the aqueous

humour formation rate does not change during pregnancy but the

outflow facility increases during pregnancy, causing a decrease in

IOP .In addition, Wilke (2009) demonstrated a decrease in

episcleral venous pressure during pregnancy is likely

multifactorial, involving hormonal mechanisms and second

messenger systems that result in increased outflow facility and in

decreased episcleral venous pressure.

The rate of aqueous formation and facility of outflow are known

to decrease with the advance in age. According to Becker (1963) it is

not known whether these are independent or related to each other,

he has reported that a decreased in rate of aqueous formation

results in the decrease in the facility of the outflow. His hypothesis

says decrease in inflow may decrease the nutritional supply of

trabecular meshwork causing variation in outflow value.

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Conversion tables to obtain Po (resting intraocular pressure) from

Pt (pressure with the tonometer on the eye) were developed from

studies done on cadaver eyes by Friedenwald. These values were

basically confirmed by McBainin studies using an adjustable

manometer. The scale reading of the tonometer with each plunger

weight was recorded.

STATISTICAL ANALYSIS

The data collected were entered in the MS excel spread sheet.

Descriptive table was generated and appropriate statistical analysis

was done using SPSS17.0 software.

ANOVA (Analysis of Variance) was applied to compare the IOP

in different phases of menstruation, pregnancy and menopause. A

significance level of p value < 0.05 was considered for the ANOVA.

The data were expressed as mean ± standard deviation.

RESULTS

INTRAOCULAR PRESSURE IN DIFFERENT TRIMESTERS OF

PREGNANCY

Table 1 shows IOP measured during first trimester in the right

eye was 16.1± 2.9mmHg and left eye was 16.1±2.7mmHg where as

during second trimester in right eye it was 13.2± 2.4 mmHg and in

the left eye it was 13.6±1.6 mmHg and during third trimester in the

Sugapriya .G et al. Int J Biol Med Res. 2014; 5(4): 4495-4498

4498

CONCLUSION

In Our study we found that there was a significant decrease in

IOP in advanced pregnancy. But no significant change was observed

in first and second trimester.

The levels of sex hormones fluctuate predictably throughout

pregnancy. There is a growing awareness that sex hormones play a

major role.

Physiologically oestrogen is a water retaining hormone, an

action manifested by increase of blood volume, rise of blood

pressure and increased body weight. Water retention could be said

to be one of the important factors in raising intraocular tension. A

rise in intraocular pressure (lOP) may offer the first sign in the

diagnosis of glaucoma hence the need to investigate the influence of

intraocular pressure in pregnancy which forms an integral part of

womanhood . (Ajayj Bosede Olajire and Idu, Faustina (2005).

The problem of glaucoma in recent years has assumed such

wide proportions as to call for a drastic reorientation in our

approach. One aspect of the subject, namely the aetiology of

glaucoma still remains shrouded in a veil of mystery

Acknowledgement: I express my sincere thanks to my

department,colleagues ,technicians for their constant

encouragement throughout my study.

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REFERENCES

Copyright 2010 BioMedSciDirect Publications IJBMR - All rights reserved.

ISSN: 0976:6685.c

Sugapriya .G et al. Int J Biol Med Res. 2014; 5(4): 4495-4498