les, it averages 18.5 mm, with the upper limit of normal reported as 24.7 mm. A separate study reported the average as 18.2 mm, with an upper normal limit of 24.14 mm in males and 22.74 mm in females.
In Mexican adults, males averaged 15.18 mm and females averaged 14.83 mm.
In Tehran, Iran, for the age group of 20-70 years, the average was 14.7 mm.
In Taiwanese adults, comparing normal subjects to those with Graves disease, the normal group had an average reading of 13.91 mm versus 18.32 mm for the Graves disease group.
Even within a group of people, there can be variability. Four ethnic groups in Southern Thailand had exophthalmometry measurement averages ranging from 15.4 mm to 16.6 mm.
In 2477 Turkish patients, the median Hertel measurement was 13 mm, with an upper limit of 17 mm.
In a Dutch study, the upper limit by Hertel measurement was 20 mm in males and 16 mm in females.
Females also show racial variation. The average in white women was 15.4 mm and the average was 17.8 mm in African American women. The upper limits of normal in each group were 20.1 mm and 23 mm, respectively.
In general, adult females across all races have lower exophthalmometry readings than adult males.
Thyroid orbitopathy has a female preponderance, with a female-to-male ratio of 5:1. However, these differences diminish for the more serve cases of ophthalmopathy. The incidence of severe ophthalmopathy is 3-5%. The female to male ratio in this subgroup is 1.4:1.[18, 2]
Proptosis occurs in both adults and children at any age. Thyroid orbitopathy and the resultant exophthalmos show a predilection for females aged 30-50 years.
Ahmadi et al showed that with increasing age occurs a "linear reduction in ocular protrusion." With advancing age, there was no asymmetries between the eyes noted.
A US pediatric population showed exophthalmometry measurements that increased with increasing age, as one would expect. The results were stratified into age groups with the following corresponding averages: Younger than 4 years: 13.2 mm
Aged 5-8 years: 14.4 mm
Aged 9-12 years: 15.2 mm
Aged 13-17 years: 16.2 mm
Of the 673 subjects in this study, only 2 had a 2-mm difference between the eyes.
In Tehran, Iran, for the age group 6-12 years, the average was 14.2 mm and for the age group 13-19 years, the average was 15.2 mm.
In Chinese children and adolescents from Xiamen, in the age range from 5-17 years, the average exophthalmometry reading was 14.48 mm.
A meticulous history of the patient's ocular and systemic systems is key in establishing a diagnosis.
The ophthalmic history should address the duration and the rate of onset of the proptosis. The patient should be queried about pain, change in visual acuity or refraction, diplopia, and decreased fields of vision. Transient visual loss or blackout periods may signify optic nerve compromise and may call for rapid intervention.
Complaints of foreign body sensation or dry gritty eyes are symptoms that may indicate corneal decompensation.
In performing a thorough medical history and a review of systems, the ophthalmologist should consider orbital involvement secondary to systemic pathology.
Past trauma and family history also may aid in the diagnosis.
Evaluation of the patient with exophthalmos begins with a thorough ophthalmic and medical history. When concomitant sinus disease or an intranasal source is suspected, a speculum or endoscopic intranasal examination is warranted. Special emphasis on the duration and rate of progression of the patient's signs and symptoms is essential. Pain, diplopia, pulsation, change in effect or size with position or Valsalva maneuver, and disturbance of visual acuity are symptoms that should be explored. In general, a difference of more than 2 mm between a person's 2 eyes is abnormal.
A complete ophthalmic examination is paramount. Periorbital changes can be noted easily on gross examination in a well-illuminated examination room.
Hypertelorism, exorbitism, eyeball protrusion (proptosis), eyelid lesions or edema, chemosis, and engorged conjunctival vessels are several periorbital signs.
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