refractive errors July 2025

Emmetropisation components

 Passive emmetropisation

 Active emmetropisation

 Visually driven mechanism

Nature

Genetics

 Ethnicity

 Family history

 Heredity is not destiny

 Myopia: is the nature-nurture debate finally over

Nurture

Myopia:

 Major increase in recent years – epidemic proportions

 Reading in the dark

 Too much close work

 Lack of sunlight

 ?evidence of change in hypermetropia

close work

In Singapore myopia increased from 25 to 80% in 18 yr old

males over 30 yr period

 BUT 70% of 18yr old men of Indian origin living in Singapore

have myopia – compared to 10% in India

Myopia and close work

Saw 2002 Arch Ophthalmol

 Books read per week

 High myopia >3D 4.3±5.8

 Low myopia 2.6±2.5

 Emmetropia 2.5±2.2

Daylight and myopia

More near work linked to less time outdoors

 Seasonal variation

 Daylight linked to release of dopamine, involved in eye growth regulation

methods of reducing myopia

manipulation of optics

• bifocals

• varifocals

• undercorrection

• contrast management

corneal reshapping

• RGP CLs

• ortho-K

Prevention of accom

• atropine

environmental

• time outdoors

• contrast management

• near activities

Contrast management

Genetics have shown:

 L or M cone photopigment gene mutations associated with abnormally

high retinal contrast signalling & highly progressive myopia

 Increased stimulation of retinal contrast pathway in CSNB is associated

with high myopia

 Reduced contrast signalling in achromatopsia is associated with

hypermetropia

 Clinical observations

 High contrast visual activities and environments associated with

progressive myopia

 dark text on a white background

 Digital devices

 Modern urban environments

Atropine

By preventing accommodation, eliminates stimulus for eye

growth

• Can reduce/halt eye growth

• BUT what are disadvantages?

• Reducing strength of eye drops 0.01%

Treatment options

Acupuncture – for myopia

light therapy

eye massager

Hypermetropia

ALSPAC

 Hypermetropia (and associated conditions) commoner in children with

fewer socio-economic advantages

 Not explained by BW, GA, perinatal illness or FH

 MEPEDS & BPEDS

 Hypermetropia significantly more common when primary care givers

education less than high school

Impact of hypermetropia

Williams 2005

 Significantly lower education scores in children aged 8 yrs

with >+3DS

 Higher rates requiring referral to educational psychologist

 Roch-Levecq 2008

 Spectacle correction improved results on visual motor

integration tasks (but only 14% hypermetropic >+4DS)

 VIP study 2016

 Uncorrected hyperopia ≥4.0 D or hyperopia ≥3.0 to ≤6.0 D

associated with reduced binocular near VA (20/40 or worse)

or reduced near stereoacuity (240 seconds of arc or worse) in

4- and 5-year-old children enrolled in preschool or

kindergarten is associated with significantly worse

performance on a test of early literacy.

Detection of hypermetropia

homson software Vision Screener

 Why +2.50DS?

 Is this level appropriate for all ages?

 How long should you allow?

 What response warrants referral?

reduced prescription for hypermetrop

giving full amount

• Best VA

   Risk of preventing

  emmetropisation

   But already impacted in the

  presence of strabismus

reduced

•  May not attain maximum VA

   May be better tolerated

undercorrecting hypermet

Under corrected by 1DS at nine months vs children with

hypermetropia who were not treated

 Evaluation between 9 and 36 months showed no significant

difference

 BUT there was considerable individual variation which could

not be accounted for

 Atkinson et al 2000

Impeding emmetropisation

Refractive error ≥+5.25D in one eye at 6 months + wore

their glasses

 Emmetropisation significantly impeded compared to

those who did not wear their glasses

 BUT emmetropisation not halted

 Ingram et al 2000

 Majority of change in refractive error occurs during 1st

yr of life

 So ? wait to prescribe until after 1yr of age

 Lack of evidence

Exceptions to the rule

• strabismus

• downs syndrome

• premature

Hypermetropia & strabismus

RCT

 Children with gls

 MSE did not decrease

 Children who developed strabismus

 MSE did not change whether in gls or not

 Ingram et al 2000

Change in refractive status was not related to early refractive

status

 BUT age at follow up during the period when

emmetropisation is incomplete.

 So we do not know if the strabismus resulted in

 Slower/delayed development of eye growth

 Long term impact

 Changes in refractive error in patients with accommodative

esotropia after being weaned from hyperopic correction BJO

2014

Anisometropia and strabismus

In strabismic patients the mean change in refraction was less

in the fellow than fixing eye

 Aniso increased in 53% of strabismics but remained

unchanged in 94% of straight eyes

evidence

Srabismus

 Suggests full correction should be given due to lack of

emmetropisation

 BUT data grouped eg all ET’s and low number of XT’s –

does one rule apply to all?

Downs syndrome

 Suggests full correction should be given because of poor

accommodation

 BUT may not be required long term

LBW

 Suggests give some correction

 BUT no comparison of with/without glasses

Long term outcomes in hypermetropia

Jaycock Ophthalmology 2005

 5 yrs post LASIK

 If initial ref error +1.00 to +3.00 D 71.0% of eyes within +/-1.00 D of

intended correction

 Initial ref error +3.5 to +6.0 D 37.5% of eyes within +/-1.00 D of

intended correction

Paediatric refractive surgery

Minority of patients

 Uses?

 Challenges

 Target refraction

 Patient cooperation

 High refractive errors

Who are the minority?

Spectacle non-compliant

 With amblyogenic anisometropia

 Bilateral ametropia exceeds 4-5D

 Children with special needs

 Eg significant craniofacial or ear deformities, hearing aids, a cochlear

implant etc

summary

Lack of standardisation of a significant refractive error

 But is it possible/appropriate to standardise?

 Evidence based practice

 Still many areas lacking in evidence eg emmetropisation and

strabismus

 Prescribe or wait and see?

 Weigh up pros and cons

 How much weight do we give to each factor