Prevalence determination of the lost of visual acuity and severe amblyopia performed for students with limited resources
Autor: Dr. Carlos Carrión Ojeda | Publicado:  16/02/2011 | Oftalmologia , Articulos | |
Prevalence determination of the lost of visual acuity and severe amblyopia .2


Examined 12,364 children aged 3 to 15, diagnosing 5,650 with ametropia:

• Slight lost of visual acuity: 3,125 students.

• Moderate lost of visual acuity: 1,710 students.

• Severe lost of visual acuity: 815 students.

The prevalence of ametropia in the population - 46.3% - of the Healthy Schools was very high compared to the 30% to 35% frequencies reported in other countries. By the characteristics of the study there were no concentrations or population dispersions. Within the total discovered ametropia, the slight type accounted for 55.31% - corrective lenses required only if subjects had visual symptoms.

The moderate type - 30.27% - almost always required refractive correction. And the severe types - 14.42%, 815 students - a number greater than that in reported statistics, required urgent treatment since this type potentially causes amblyopia.

There is no significant difference with respect to the presence lost of acuity vision between the sexes; the greater tendency (53%) of the presence of lost of acuity vision is in females.


A significant association exists between type of severe lost of acuity vision and amblyopia in the combined school population. Chi - square (7.07), significance (p =0.029).


Lostvisual acuity and ametropiaassociated was discovered in 46.3% of the population without any type of concentration or dispersion, a greater percentage compared to the 30% to 35% frequencies reported in the studies performed in other countries - 5,6,17,21,25.

A greater tendency (53%) of the presence of ametropia was apparent in the female group. The greater relative percentage of the population afflicted with ametropia was within the group aged 6 to 9. The percentage of ametropia in the students varies between 30% and 75% in the different schools. Students with severe ametropia or amblyopia were referred to the Child Health Institute for specialized treatment.

When amblyopia was diagnosed within the severe lost vision acuity population in the third stage of the study, the parents of the students were questioned as to their children’s use of glasses. Only 9.75% responded that their children had used glasses and some of those admitted that their children, for whatever reason, had not used their glasses continuously; 90,25% of the parents responded that their children had never used glasses, and the parents were moreover unaware of the health problem that their children had.

Pathological and ethiological causes of ametropia associated: Is well-known that ametropia is hereditary, but some authors have revealed that other factors such as precocious underfeeding or low weight at birth may be prompters of the disease - 9,20,24. This would explain the different results obtained in our study with respect to other facts discovered in the U.S.A. and in other developed countries.

Behavior of lost of visual acuity and amblyopia: The prevalence of amblyopia within the severe cases of lost of vision acuity of the five districts pertaining in the South of Lima is 39%. Four of each ten who suffer severe lost of vision acuity are afflicted with amblyopia.

It is moreover necessary to consider ambliopes, which are caused by moderate lost of visual acuity. Moderate lost of visual acuity and associated ametropia also contributes, albeit in smaller relative proportion, to ambliopía - 7,8,10,11. Whatever increases the number of ambliopes found in this study could be similar all over Peru because the sample is significant and in general population. There is no significant difference of the presence of lost of visual acuity between the sexes.

A significant association exists between type of severe ametropia and ambliopía in the students population. Chi - square (7,07) and significance (p =0,029). Cylindrical ametropia is the greater cause of ambliopía for the purposes of this study. Some 55.55% of cylindrical amétropes translate into ambliopia compared to the 31.34% of spherical / cylindrical ametropes that translate into ambliopia. In our study spherical ametropes generally didn’t translate into amblyopia; there were only a few cases.


There was a high prevalence (46.30%) (p< 0,01). of lost of visual acuity in the students of the schools studied. Living in extreme poverty, these students have few resources and are undernourished. The greater relative frequency of ametropia was evident in the group aged 6 to 9 - (47.46% masculine and 53.95% feminine). That means that this group has greater probabilities of ametropia, the level of physiological visual development that is reached in this tactically important point that occurs by age 6, the time at which vision must be totally developed.

It is essential to control visual sharpness at this age, visual clarity quite simply accomplished with the Snellen “directional E” card because all healthy children have developed their spatial orientation completely at this age and are completely familiar with the alphabet. The high prevalence (39%) of amblyopia due to severe lost (14.42%) of visual acuity can be attributed mainly to the evidence that only 9.75% of those studied used lenses.

For this reason, the strategies to apply in Peru and in other poor countries with a similar population type must be different from those applied in first-world countries. It would also be advisable to pay closer attention to improving the nutrition of both the pregnant women and the suckling babies in these populations. Amblyopia is predictable and requires ever improving interinstitutional strategies between the Health and Education sectors.

Solid ocular health policies and affordable corrective products and services conscienciously steered by the State or by ONGs are required to help, with lenses and therapy, those stricken to recover. On the basis of the conclusions of our investigation, our group proposes the following recommendations:

To doctors and other healthcare personnel: Possible early detection of lost visual acuity in students and references to an ophthalmologist.

To ophthalmologists: Create public awareness (especially in the high probability populations) as to the causes of amblyopia and early diagnosing in students. Jointly work with pediatricians and other doctors and nurses.

To ocular healthcare service providers: Strive to arrive at such oriented strategies to diminish the frequency of amblyopia as the diffusion of causes of ametropia and amblyopia between doctors and ophthalmologists. Educate the general public about ametropia and amblyopia natural science courses and other educational programs. Create interinstitutional Health-Education committees to review the presence of ametropia and amblyopia in students before age 5. And, follow up with pertinent corrective measures in all cases of amblyopia or severe ametropia.

To international ocular healthcare service providers: Institute studies of prevalence and of risk factors of ametropia and amblyopia in populations with precocious underfeeding and also their correlation with student yield will improve the future quality of life of the children. The outlook of any country improves with its constant investment in child healthcare.


This study was awarded the National Institute of Child Health Prize for our Investigation of Child Health, Version 2008, winning first place.


To ONG “Land of Children” and “Aid in Action Foundation“ and to the INSN (Children’s Hospital of Peru) for their support.
To Promotional Schools of Health, Healthy Schools, for its support and participation.

To Nelly, Rosa, and Arie for their love, time, support, and understanding.


Authors have not commercial or financial interest in products described or reported in the manuscript that may give rise to the perception of a potential conflict of interest.


The present study was carried out according to the postulated ethical contained in the Declaration of Helsinki and successive declarations that have upgraded referrals postulates.

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