Influence of chronic alcohol abuse and ensuing forced abstinence on static subjective accommodation function in humans

In¯uence of chronic alcohol abuseand ensuing forced abstinence onstatic subjective accommodation functionin humans

Hugh Campbell, Michael J. Doughty, Gordon Heron and RogerG. Ackerley

Department of Vision Sciences, Glasgow-Caledonian University, Glasgow G4 OBA, UK

Summary

Purpose. Acute alcohol ingestion can change accommodation, but the long term effects ofsustained alcohol consumption on accommodative function have not been studied in detail. Thisstudy was thus undertaken on individuals with a history of alcohol abuse.

Methods. Thirty-seven male individuals aged 25±56 years (average 40 years) from an alcoholrehabilitation centre in Inverness, Scotland, were assessed on admission and after a week offorced abstinence. The results were compared to a paired age-matched set of control malesubjects. The static amplitude of accommodation was measured by an RAF rule, and the pupilsize measured with a pupil gauge.

Results. On admission, the group mean measured amplitude of accommodation was 4:7 ^ 2:2 D(mean ^ SD). These values for the alcoholics were lower than age-matched controls (of 5:9 ^ 2:9 D�:The slope of the age-dependent decline in RAF rule accommodation measures was signi®cantlysmaller for the alcoholics compared to controls (at 0:215 ^ 0:027 D=year versus 0:332 ^0:015 D=year; respectively; p , 0:001�; with the younger alcoholics showing a greater impairment.Following abstinence, there was no measurable change in accommodation measured, indicatingthe lower amplitude in the alcoholics was not attributable to circulatory alcohol levels. The restingpupil diameter in the alcoholics was 4:37 ^ 0:63 mm compared to the controls of 3:97 ^ 0:75 mm;with a higher incidence of small pupils (#3 mm) in the controls.

Conclusions. The results indicate that chronic alcohol use can adversely affect subjective staticaccommodation, especially in younger alcoholics, as well as cause slight mydriasis. q 2001 TheCollege of Optometrists. Published by Elsevier Science Ltd. All rights reserved.

Introduction

A British Medical Association booklet for patients in the

late 1980s states that an average GP practice with 2000

patients aged between 15 and 75 would have 340 patients

who were drinking above sensible limits; 19 would be

classi®ed as dependent drinkers, i.e. alcoholics. Routine

optometric assessment of the near vision of such patients

referred from GPs indicated a precocious requirement

for reading additions in spectacles. For example, one emme-

tropic individual with complaints of photophobia, lacrima-

tion and blurred vision for close work, was found to require

a 11.50 DS reading addition despite his age of 35 years.

The consultant ophthalmologist, to whom he was referred,

concluded that his symptoms were probably related to

chronic alcohol consumption. A further investigation

seemed warranted for while there have been a number of

reports on the acute effects of alcohol consumption on

accommodation, the effects of chronic alcohol abuse of

the accommodation do not appear to have been established,

and such individuals are more likely to visit an optometric

practice.

The effect of alcohol consumption on vision has long

197

Ophthal. Physiol. Opt. Vol. 21, No. 3, pp. 197±205, 2001q 2001 The College of Optometrists. Published by Elsevier Science Ltd

All rights reserved. Printed in Great Britain0275-5408/01/$20.00

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PII: S0275-5408(00)00029-6

Received: 29 November 1999

Revised form: 10 April 2000

Accepted: 26 June 2000

Correspondence and reprint requests to: Michael J. Doughty. Tel.: 144-

141-3313393; fax: 144-141-3313387.

E-mail address: [email protected] (M. J. Doughty).

attracted attention (Goldberg, 1943; Watten and Lie, 1996;

Wegner and Fahle, 1999), especially since the adverse

effects of ethanol on visual function can have substantial

social and economic impacts including safety of the public

at large (Stapleton et al., 1986; Hindmarch et al., 1992). The

acute effects of alcohol consumption on accommodation

and related functions of the eye have been assessed

(Cohen and Alpern, 1969; Levett and Karras, 1977;

Hogan and Lin®eld 1983; Wilson and Mitchell, 1983;

Hogan and Gilmartin 1985; Miller et al., 1985, 1986; Hill

and Toffolon, 1990; Watten and Lie, 1996) and while the

outcomes from such studies have been rather mixed (see

Discussion), these types of investigations can be considered

as assessments of the impact of CNS depression on oculo-

motor function; ethanol is a potent CNS depressant drug

(Nutt and Peters, 1994). A neurological basis to the effects

of chronic excessive alcohol consumption (i.e. more than 21

units/week) has been explored by assessment of pupillary

function (Skogland, 1943; Schleyer and Wichmann, 1961;

Brown et al., 1977; Myers et al., 1979; Rubin et al., 1980;

Tan et al., 1984; Miralles et al., 1995) or corneal sensitivity

(Goldberg, 1943). The results of such studies have also been

inconclusive, perhaps as a result of the various control

groups not being well de®ned.

The present study was designed to compare accommodative

function and pupil status in a group of chronic alcoholics,

rehabilitating in a residential centre. The assessment of

possible dysfunction was made by comparison with a

de®ned group of age- and spectacle correction-matched

non-alcoholic individuals. A further part of this study was

to re-measure these aspects of visual function after one

week's supervised abstinence from alcohol consumption.

After this period of time it can be reasonably assumed that

all traces of alcohol in the body have been metabolised

(Lands, 1998). These latter measures therefore allow one

to determine what the effects of alcohol itself, rather than

alcohol per se, have on visual function.

Methods

Study subjects and study design

Two groups of individuals were recruited for this study,

namely 37 diagnosed male alcoholics and 37 age- and

spectacle-matched (paired) controls who consumed less

than 21 units of alcohol/week. The alcoholic subjects,

with a history of 5±15 years of alcohol abuse, were assessed

by clinical staff using the DSM-III-R (Diagnostic and

Statistical Manual of Mental Disorders) system. The

Highlands Psychiatric Research Group (HPRG; Highland

Health Board, Inverness) provided approval for the study

and facilitated access to the subjects to one of us (H.C.). Part

of the diagnosis of alcohol abuse was based on blood plasma

levels of the enzyme gamma-glutamyl transpeptidase

(GGT) and the red blood cell mean corpuscular volume

(MCV). These measures, when certain cut-off values are

applied, provide an indication of liver damage caused by

the alcohol abuse (Yersin et al., 1995). Blood samples were

taken by HPRG staff, analysed on site and also sent to

Scotia Pharmaceuticals (NS, Canada) for further analyses.

The mean GGT levels, an indicator of liver damage, were

113 ^ 96 Units/L (median 93 Units/L, range 17±366 Units/

L). With a cut off of 50 Units/L for alcoholic abuse (Yersin

et al., 1995), 31 (83.8%) of the individuals would be

classi®ed as positive for alcohol abuse. The MCV averaged

95:3 ^ 5:54 fentoL, median 96 fentoL, which with an upper

limit of normal of 95 fentoL, would mean that only 25

(67.6%) of the alcoholics would be classi®ed as positive

for alcohol abuse with this red blood cell test. The patients

were admitted on a voluntary basis with agreement to

monitored abstinence. They were assessed shortly after

admission to the centre and abstinence was enforced by

behaviour monitoring and random breathalyser checks,

e.g. after exercise breaks or visitation by family members.

The control male subjects were recruited from the opto-

metric practice of one of us (H.C.), after having the study

protocol explained to them and written consent forms were

signed. None of the control group were taking any medica-

tions, and had no ocular abnormality other than refractive

error and their VA was 6/9 or better. This group of control

subjects were age-matched to the alcoholics and with a

refractive error match to within ^0.5 DS, and usually to

within ^0.25 DS. The control subjects were provided with

an information lea¯et explaining what a unit of alcohol was

and were asked to keep a drinks diary of any alcohol

consumed (so as to conform with the upper-advised limit

of casual consumption of alcohol). All control subjects were

designated sober at the time of the assessments.

Measurements taken at the start of the study (designated

as admission for the alcoholics subjects) have been signi®ed

as T1 and a second assessment (T2) was made on the

alcoholics after a period of forced abstinence of seven

days. For practical reasons, these assessments and the

corresponding two measurements taken on the control

group were carried out at any time during the working

day. All subjects were identi®ed by a numerical code.

Clinical assessments

All subjects in the study had refractive error, amplitude of

accommodation and pupil size assessed. For measures of

static accommodation, a near-point rule (an RAF rule;

Clement Clarke, UK) and a modi®ed RAF rule utilising

the principle of the Badal-type optometer (Bennett, 1977)

were used monocularly. For the RAF rule, the distance for

clear resolution of the N5 type was assessed ®ve times for

both incoming (up measures to blur) and receding (back

measures to achieve clarity) presentation of the target

(which was manually moved along the 50 cm rule). The

Badal-type optometer had a 18.00 DS lens mounted on

198 Ophthal. Physiol. Opt. 2001 21: No 3

the RAF rule with the second focal point coincident with the

anterior focal point of the eye. The upper limit of measure-

ment with this device is limited to 8 D, but it was felt that

this would not be a signi®cant limitation, since the alcoholic

subjects were expected to have low amplitudes of accom-

modation. Pupil measures were taken to 0.5 mm accuracy

using an ophthalmic rule with black semicircles along its

edge, with the subjects ®xating on a distant Snellen acuity

chart. Room illumination was controlled for both measures,

so that the chart luminance was set at approximately 150±

250 cd/m2.

Statistical analyses

Graphic presentation and statistical analyses were carried

out on Systat Version 8.0 (Systat Inc., Evanston, IL, USA)

and were principally based upon the use of a paired Students

t-test (since the alcoholic subjects were age- and spectacle-

matched with a set of control subjects). Linear regression

analyses were used to assess age-dependent changes in the

clinical measures. Level of statistical signi®cance was set at

p , 0:05:

Results

The study subjects

The two groups of study subjects were age-matched by

pairing a control subject to each alcoholic. The average age

in both groups was thus 40:4 ^ 8:4 years �n � 37 each,

mean ^ SD), with a median value of 40 years for the age

range of 25±56 years. The pairing was also designed to

match refractive errors as reasonably as possible (Table 1),

and the difference between the groups was not signi®cantly

different. Astigmatism in the subjects was limited to

^2.0 D, and was mostly much less than this or non-existent.

The spectacle prescriptions for 18 of the alcoholics included

a near-point addition of 0.50±2.00 D (average 1.28 D),

while just 12 of the controls had a near-point addition of

0.50±2.25 D (average 1.21 D).

Measurement of accommodative function in alcoholics on

admission

The average RAF rule measures in the alcoholics at the

®rst assessment (T1) was 4.65 D from ®ve measures of the

response to an inwardly moving target (up or positive

measures), and averaged 4.60 D for the reverse response

(back or negative measures) (Table 2). The distribution of

all forward and back values was normally distributed about

the modal value of 4.5 D (e.g. Figure 1A), as assessed by a

Komologorov±Smirnov test �p , 0:05�; and the median

amplitudes were 4.8 D for both positive and negative

measures of accommodation (range 0±9 D). The variance

across the ®ve measures did not exceed 0.5 D (average 11%)

for any one subject for either response and the overall

variance between subjects, expressed as a standard

deviation, was 2.23 and 2.31 D, respectively, for the two

assessments. A similar result was obtained with a Badal-

type optometer, with average responses for the forward

and back tests being 4.0 ^ 2.6 D and 4.0 ^ 2.6 D,

respectively (mean ^ SD), with median values of 3.5 D

(Table 3).

There was the expected age-dependent decline in

amplitude of accommodation as assessed by the RAF rule

(Figure 2A), using forward or back response measures. Over

the age range of 25±56 years, linear regression analyses

(using the averaged RAF rule data from the forward and

back measures) showed the age-dependent decline in static

accommodation to be statistically signi®cant �p , 0:001; F

ratio 65.272, r2 � 0:651� and to have a magnitude of

20.215 ^ 0.027 D/decade (mean ^ SE of estimate).

In¯uence of chronic alcohol abuse on static subjective accommodation function: H. Campbell et al. 199

Table 1. Subject characteristics

Subject group Age (year) (mean ^ SD) Distance refractiveerror (DS)

(mean ^ SD)

Best correcteddistance refractive

error (D)(mean ^ SD)

Controls 40:4 ^ 8:4 0:10 ^ 1:03 0:21 ^ 0:94Alcoholics 40:4 ^ 8:4 0:07 ^ 1:08 0:19 ^ 0:96

Table 2. Static accommodative function measured by an RAF rule in normal subjects and alcoholics before and after forcedabstinence

RAF rule T1a upmeasures (D)

RAF rule T2 upmeasures (D)

RAF rule T1 backmeasures (D)

RAF rule T2 backmeasures (D)

Normal subjects 5:86 ^ 2:88 5:88 ^ 2:89 5:83 ^ 2:87 5:85 ^ 2:88Alcoholics 4:65 ^ 2:23 4:60 ^ 2:22 4:60 ^ 2:31 4:61 ^ 2:34

aT1 measures were made on admission and T2 measures after abstinence.

Measurement of accommodative function in age-matched

control group

For the controls, RAF rule measures produced average

values of 5:86 ^ 2:88 and 5:83 ^ 2:87 D (mean ^ SD) for

the forward and back responses, respectively, with median

values of 6.30 D in each case. A range of average values

from 1.2 to 10 D was encountered (Figure 1B). The variance

across measures did not exceed 0.5 D (average 7%) for

any individual subject. As assessed using a Badal-type

optometer, rather lower average values of 4:6 ^ 2:3 D

were obtained (Table 3), because of the upper limit to the

optometer measures of 8 D. The RAF rule and Badal-type

optometer thus produced statistically different measures for

the control subjects �p , 0:001; 36 DF, mean difference

1.23 D), while such a difference between measurement

techniques was not seen in the alcoholic group.

The measured amplitude of accommodation in the control

group decreased as a function of age (Figure 2B), with the

age-dependent decline being estimated with a simple linear

regression model to be 20.332 ^ 0.015 D/decade (mean ^

SE of estimate, p , 0:001; F ratio 477.461, r2 � 0:932�:

Re-assessments of accommodative function in alcoholics

and control subjects

All of the alcoholics were re-assessed after a 7-day period

of abstinence and the control subjects were also

re-assessed after a similar time period. There was no statistical

difference �p � 0:908; Student's t-test for paired samples) in

the measures for the alcoholics when the results at T1 and

T2 were compared from the RAF rule (Table 2) or Badal-

type optometer (Table 3).

A similar constancy was also found for the control

subjects at T1 and T2 (Tables 2 and 3) with, for example,

the measures with the RAF rule not being different �p �0:971; Student's t-test for paired samples).

Comparison of accommodative function in alcoholic to age-

matched control subjects

The age-dependent decline in static accommodative

function, as assessed with an RAF rule, was signi®cantly smal-

ler �p , 0:001� in the alcoholics compared to their age-

matched paired controls (Figure 3). Both the alcoholics and

controls had close to zero amplitudes at $50 years of age. The

overall difference between the entire group of alcoholics and

their age-matched controls is shown as a box plot in Figure

3A. The median values are clearly different (at 4.80 and

6.30 D for alcoholics and age-matched normals). While

the inter-quartile intervals do overlap substantially, the

two sets of data were signi®cantly different when compared

by the Mann±Whitney U test �U � 503:500; p � 0:050�and a Chi-square across measures analysis was also signi®-

cant �x � 3:833�: When the RAF rule accommodation


Table 3. Static accommodative function measured by a Badal-type optometer in normal subjects and alcoholics before and afterforced abstinence

BADAL T1a upmeasures (D)

BADAL T2 upmeasures (D)

BADAL T1 backmeasures (D)

BADAL T2 backmeasures (D)

Normal subjects 4:63 ^ 2:32 4:64 ^ 2:32 4:63 ^ 2:32 4:64 ^ 2:32Alcoholics 4:02 ^ 2:59 4:16 ^ 2:53 3:97 ^ 2:63 4:15 ^ 2:55


Figure 1. Distribution of measures of static amplitude of accommodation (up measures) in alcoholic subjects (A)and control subjects (B) at ®rst assessment (T1).

measures for the alcoholic and control group were compared

using a Student's t-test at either T1 or T2, a signi®cant

difference was also found �p , 0:025�; but the set of control

data was not as uniformly distributed as in the alcoholic

group (KS p . 0:1� and so less reliance can be placed on

this statistical test. Since the measured accommodation in

each group clearly declines to close to zero dioptres in the

®fth decade, this means that the younger alcoholics (#40

years of age) had a disproportionately lower amplitude of

accommodation than age-matched controls. This is shown in

the box plot in Figure 3B where the amplitude of accom-

modation for all the subjects in both groups #40 years �n �20� are compared. There is now essentially no overlap for

the inter-quartile intervals, and the difference is highly

statistically signi®cant �p , 0:001 Mann±Whitney U test,

p , 0:001 paired Students t-test). Within this smaller group

of 20 pairs of subjects aged #40 years, all of the pupil

diameters were $3.5 mm (see below and discussion).

Pupil diameter assessments and potential effect on RAF rule

accommodation measures

The average resting pupil diameter in the alcoholic

subjects was 4:37 ^ 0:63 mm (mean ^ SD, range 3±

5.5 mm, median 4.5 mm), while the comparative value for

the control group of subjects was 3:97 ^ 0:75 mm (range

2.5±5.5 mm, median 4.0 mm); this net difference of

0.39 mm (paired samples) was statistically signi®cant

(paired Student's t-test p 0.001, DF 36; signed rank test, p �0:003� (Table 4).

The measured resting pupil diameter values were depen-

dent on the age of the subjects for both the alcoholics

(Figure 4A) and the controls (Figure 4B). With more of

the control subjects showing small pupils (i.e. #3 mm),

the age-related decline was more substantial in the control

subjects. Regression analysis indicates an age-dependent

decline in resting pupil diameter of 0:057 ^


Figure 3. Box plots to show differences between static amplitude of accommodation (up measures) in all alcoholicand control group subjects at ®rst assessment. (A) All 37 subjects, (B) subjects #40 years of age. The box showsthe median value and the 50% inter-quartile interval, while the bars show ^1.5 SD from the mean value. For thetwo plots, the abbreviations A and N indicate the alcoholic and normal control subjects, respectively.

Figure 2. Measures of static amplitude of accommodation (up measures) in alcoholic subjects (A) and controlsubjects (B) at ®rst assessment (T1) as a function of age. A very similar relationship was seen for back measuresand for both measures at second assessment (T2).

0:008 mm=year for the alcoholics, and 0:075 ^

0:008 mm=year for the controls. At T1, for example, one

of the alcoholics and six of the control group had pupil

diameters of 3 mm or less. An argument could be made

therefore that the very small pupil diameters adversely in¯u-

enced measures of static accommodation. However, exclu-

sion of those paired sets of data that included subjects with

pupil diameters of 3 mm or less, did not remove the overall

difference in RAF accommodation measures, e.g. at T1, the

amplitudes averaged 5:36 ^ 1:9 D for the alcoholics and

6:87 ^ 2:36 D for the controls. The average difference

was 21.50 D, which was statistically signi®cant (DF 28,

p , 0:001�: For those pairs of subjects aged #40 years,

all the pupil diameters were $3.5 mm, and averaged 4:73 ^

0:47 mm for the alcoholics and 4:48 ^ 0:55 mm for the

controls; the average difference of 0.25 mm was not statis-

tically signi®cant (19 DF, p � 0:116�: Similarly, if the data

from these seven pairs of individuals is excluded, the pupil

difference still exists, i.e. the pupil diameter in the alcoholic

group was marginally greater than in the controls �4:57 ^

0:53 mm vs. 4:24 ^ 0:59 mm�; the average difference

across the paired samples was 0.328 mm, which was statis-

tically signi®cant using a paired t-test (DF 28, p � 0:011�(Table 4).

Discussion

As mentioned in the introduction, the present study was

prompted by observations in optometric practice on the need

for near vision spectacle additions in alcoholic individuals.

The results do indicate that chronic alcoholics can indeed

suffer from a reduced static amplitude of accommodation.

This de®cit was reproducible in that it did not improve

following a week of abstinence from alcohol consumption.

It is acknowledged that individuals can have substantially

different alcohol clearance rates (Lands, 1998), but the time

elapsed between admission and assessment should have

been suf®cient to reduce blood alcohol to minimal levels.

For the alcoholic subjects, therefore, the impaired static

accommodation could not be obviously attributed to the

short term effects of ethanol and/or a high blood alcohol

level (BAL).

The measured amplitude of accommodation generally

starts to decline in early adolescence but various estimates

have been made to determine the rate of decline in accom-

modation with age after 25 years (Turner, 1958; Ayrshire

Study Circle, 1964; Hofstetter, 1965; Charman, 1989;

Koretz et al., 1989; Atchison, 1995; Mordi and Ciuffreda,

1998). Published data was extracted from the papers and

regression analyses performed (Table 5). A linear regression

analysis was used and although this is not considered

applicable beyond the age of about 48 years (Charman,

1989), it can be used as a way of comparing different reports

(Ramsdale and Charman, 1989). The results of these

analyses indicate that the control group in the present

study (with a rate of decline of 0.332 D/year) are generally

consistent with these previous ®ndings.

The measurements in the present study were all taken


Figure 4. Measures of resting pupil diameter as a function of age in alcoholic subjects (A) and control subjects (B).

Table 4. Pupil diameters in normal subjects and alcoholics before and after forced abstinence

Subject group T1a measures(mm ^ SD)

Median T1(mm)

T1 range(mm)

T2 measures(mm ^ SD)

Median T2(mm)

T2 range(mm)

Normals 3.97 ^ 0.75 4.00 2.5±5.5 3:95 ^ 0:76 4.00 2.5±5.5Alcoholics 4.37 ^ 0.63 4.50 2.5±5.5 4:32 ^ 0:68 4.50 3.0±5.5


monocularly so as to remove the blurring effect of poor

convergence and extraocular muscle control when viewing

the target binocularly. This was done mainly because of

reports on the alteration of convergence and AC/A ratios

in relation to BAL following acute alcohol intake (Cohen

and Alpern, 1969; Hogan and Lin®eld, 1983; Wilson and

Mitchell, 1983; Hogan and Gilmartin, 1985; Miller et al.,

1986; Hill and Toffolon, 1990). Such alterations could have

an impact on binocular measures of accommodation (Miller

et al., 1985, 1986).

As noted in the introduction, a number of investigators

have considered whether chronic alcohol consumption

could cause a peripheral neuropathy, and have made studies

on the pupil or its re¯exes (Skogland, 1943; Schleyer and

Wichmann, 1961; Myers et al., 1979; Rubin et al., 1980;

Tan et al., 1984; Miralles et al., 1995). Schleyer and

Wichmann (1961) could ®nd no consistent effect of BAL

(0.6±2.4 mg/%) on pupil diameter, but do not provide

details (e.g. age) of the large group of individuals they

studied. An overall dose-dependent reduction in the overall

speed of the pupillary light re¯ex was, however, noted

(Schleyer and Wichmann, 1961). Rubin et al. (1980)

reported that the resting pupil diameter in darkness was

c.0.4 mm smaller in alcoholics compared to controls (of

6:23 ^ 0:37 mm�; and that the pupil diameter in bright

light for the alcoholics averaged 3.10 mm compared to

3.29 mm in the controls. The average age of the alcoholics

group was, however, 40 years (range 25±50 years) and the

average age in the controls was 28.5 years (range 21±40

years). Tan et al. (1984) reported that the resting pupil

diameter under ªstandard lighting conditionsº for alcoholics

(aged 40±69 years) with vagal neuropathy was 4:95 ^

0:97 mm; compared to 4:49 ^ 0:70 mm in an age-matched

group (aged 40±75 years). For another group of alcoholics

without evidence of vagal neuropathy, but some evidence of

peripheral neuropathy, the resting pupil size was smaller

than that found in controls, but this is likely due to larger

numbers of younger subjects in the control group used for

that comparison. Over the age interval of 40±50 years, the

age-related decline in pupil diameter was slightly more

pronounced in alcoholics with vagal neuropathy compared

to another group of alcoholics, but both alcoholic groups

showed similar age-dependent decline to control subjects

(that could not be statistically separated due to a rather

large variance in the data especially for the control group,

and those with vagal neuropathy). For a group of alcoholics

with evidence of peripheral neuropathy and aged 20±71

years (average 45.6 years), pupil cycling time was reported

to be signi®cantly slowed at 1286 ^ 297 ms; compared to

control values which were 1027 ^ 161 ms from a control

group aged 27±72 years (Miralles et al., 1995). The effect

was most pronounced in those alcoholics with advanced

vagal neuropathy (average 1500 ms), but in none of the

groups was resting pupil diameter provided. Such an effect

needs to be very much distinguished from the miosis and a

reduced, or totally absent pupil light re¯ex can be expected

in severe intoxication. In severely affected chronic

alcoholics Wernicke's encephalopathy may be present

(Jones et al., 1975), but the HPRG carried out interviews

with prospective subjects for the study, and eliminated all

those who may have reached this advanced stage of neural

damage. The pupil results obtained in the present study may

also be affected by the fact that most of the alcoholics

smoked very heavily during rehabilitation (Furuta and

Miyao, 1992). Notwithstanding, the ®nding of a slight

mydriasis in the alcoholics would be consistent with a slight

parasympathetic neuropathy.

Some of the resting pupil sizes encountered in the present

study were, as expected, rather small as a result of the age-

dependent decline in pupil diameter (Winn et al., 1994). The

resting pupil diameter for the subjects assessed in the present

study was found to be very slightly larger in the alcoholics,

although the pupil size during accommodation to the near

target could have been substantially different from this and

was not measured in the present studies. The age-related

change per year in pupil diameter was rather greater (at an

estimated 0.075 mm and 0.057 mm/year, for the controls

and alcoholics, respectively) compared to the 0.032 mm/

year for the age interval of 20±85 years reported by Winn

et al. (1994) at 220 cd/m2, but their regression plots do


Table 5. Estimates of rate of decline in subjective amplitude of accommodation in humans between the age of 25 and 55 years:cross-sectional studies

Authors Year Amplitude at 25years of age

(D)a

Rate of decline D/year(25±55 years)b

Duane 1912 10.2 20.337 (25±50 y)Turner 1958 7.9 20.263Ayrshire Study Circle 1964 5.2 20.207 (37±52 y)Sun et al. 1988 6.6 20.17 (25±46 y)Koretz et al. 1989 8.0 20.307Mordi and Ciuffreda 1998 9.7 20.34Campbell et al. 2000 10.0 20.332

aAverage values are given for subjective (push-up) measures.bLinear regression analyses were performed for the 25±55 year age interval only, unless otherwise speci®ed.

suggest that there is a faster decline between 25 and 50

years. The size of the pupil under photopic conditions

should not affect the refraction greatly, but the depth of

®eld will alter depending on the pupil diameter (Hennessy

et al., 1976; Ward and Charman, 1985). It could be argued

that the depth of ®eld factor could have resulted in accen-

tuated amplitude of accommodation measures in those

subjects with pupil diameters of #3 mm. Comparative

analyses of just those pairs of individuals with resting

pupil diameters of $3.5 mm revealed the that the alcoholic

group still had an reduced amplitude of accommodation,

and the younger alcoholics (with larger pupils) had a greater

de®cit in accommodation.

Conclusions

The present studies indicate that chronic alcoholics,

especially if aged less than 40 years, could have a reduced

static accommodation and that this could precipitate a need

for an early near point spectacle correction, e.g. in recover-

ing alcoholics with an interest in reading or other close work

for example. While the mechanism underlying this change

cannot be de®ned from the present type of studies, the

results are consistent with alcohol abuse causing a form of

peripheral parasympathetic neuropathy.

Acknowledgements

Special thanks to the staff at the Highlands Psychiatric

Research Group (HPRG; Highland Health Board, Inverness)

for their invaluable assistance with the design and scheduling

of the present study, and to the subjects who gave of their

time to participate.

References

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Influence of chronic alcohol abuse and ensuing forced abstinence on static subjective accommodation function in humans