The Tomey EM-4000 Specular Microscope is designed to observe and analyze corneal endothelium.

The Tomey EM-4000 Specular Microscope is designed to observe and analyze corneal endothelium by capturing an image of corneal endothelium tissues. without making contact, analyzing the captured image, and calculating data such as cell density.

Inclusion Criteria-Non-pathologic young adults (18-28 years old) and non-pathologic adults (29-80 years old)

1. Male or female subjects from 18 to 80 years old who have full legal capacity to volunteer on the date the informed consent is signed;
2. Subjects who can follow the instructions by the clinical staff at the clinical site, and can attend examinations on the scheduled examination date;
3. Subjects who agree to participate in the study.

Inclusion Criteria -Pathologic adults (29-80 years old):

1. Male and female subjects from 29 to 80 years old who have full legal capacity to volunteer on the date the informed consent is signed;

2. Subjects who can follow the instructions by the clinical staff at the clinical site, and can attend examinations on the scheduled examination date;

3. Subjects who agree to participate in the study;

4. At least one eye with any of the following conditions:

   1. History of post-op surgical trauma including pseudophakic or aphakic bullous keratopathy
   2. History of corneal transplant
   3. Physical injury or trauma to the cornea
   4. Fuch's dystrophy, Guttata or other corneal endothelial dystrophies
   5. Keratoconus
   6. Long-term polymethyl methacrylate (PMMA) contact lens use (greater than 3 years).

Exclusion Criteria - Non-pathologic young adults (18-28 years old) and non-pathologic adults (29-80 years old)

1. History of post-op surgical trauma including bullous keratopathy;
2. History of corneal transplant;
3. Evidence of physical injury or trauma to the cornea;
4. Fuch's dystrophy, Guttata or other corneal endothelial dystrophies;
5. Keratoconus;
6. Long-term PMMA contact lens use (greater than 3 years);
7. History of cataract, refractive or ocular surgical procedures that render the cornea opaque or otherwise impact its ability to be imaged using the investigational device;
8. Fixation problems which may prevent obtaining good Tomey EM-4000 and Konan CellChek XL images in either eye.

Exclusion Criteria - Pathologic adults (29-80 years old)

1. History of cataract, refractive or ocular surgical procedures that render the cornea opaque or otherwise impact its ability to be imaged using the investigational device;
2. Fixation problems which may prevent obtaining at least poor quality Tomey EM-4000 and Konan CellChek XL images in either eye.

Subjects recruited can be male or female, of any race or ethnicity, ages 18-80 years of age at Visit 1. All subjects enrolled must meet all the inclusion criteria and none of the exclusion criteria.