pressure (IOP) can be measured by tonometry devices. The eye can be thought of as an enclosed compartment through which there is a constant circulation of fluid that maintains its shape and internal pressure. Tonometry is a method of measuring this pressure using various instruments. The normal range is 10-21 mmHg. Retinal examination Examination of retina (fundus examination) is an important part of the general eye examination. Dilating the pupil using special eye drops greatly enhances the view and permits an extensive examination of peripheral retina. A limited view can be obtained through an undilated pupil, in which case best results are obtained with the room darkened and the patient looking towards the far corner. The appearance of the optic disc and retinal vasculature are also recorded during fundus examination. A red reflex can be seen when looking at a patient's pupil through a direct ophthalmoscope. This part of the examination is done from a distance of about 50 cm and is usually symmetrical between the two eyes. An opacity may indicate a cataract. Retinal vessel analysis is a non-invasive method to examine the small arteries and veins in the retina which allows to draw conclusions about the morphology and the function of small vessels elsewhere in the human body and is used in particular by cardiologists as well as ophthalmologists. Eye exams for children It is often recommended that children should have their first eye exam at six months old, or earlier if a parent suspects something is wrong with the eyes. Across the world, screening programs are important for identifying children who have a need for spectacles but either do not wear any or have the wrong prescription. Children need the following basic visual skills for learning: Near vision Distance vision: Tumbling E chart, Landolt C chart Eye teaming (binocularity) Eye movement Accommodation (focusing skills) Peripheral vision Eye–hand coordination Conditions diagnosed during eye examinations Myopia Hyperopia Presbyopia Amblyopia Diplopia Astigmatism Strabismus Specialized eye examinations Color vision Stereopsis Near point of convergence Keratometry Cycloplegic refraction Accommodative system Amplitude of accommodation Negative relative accommodation Positive relative accommodation Vergence system Optokinetic system Amsler grid Gonioscopy Corneal topography Corneal pachymetry Scheimpflug ocular imaging Retinal tomography Ocular computed tomography Scanning laser polarimetry Electrooculography Electroretinography Ultrasound biomicroscopy Maddox rod Brock string Convergence Testing Worth 4 dot test Pulfrich effect See also Binocular vision Eyeglass prescription Orthoptics Retinoscopy Stereopsis Subjective Refraction Vergence References External links