The slit-lamp microscope is one of the most commonly used diagnostic instruments in ophthalmology. It is employed to examine the anterior segment of the eye, including the eyelids, conjunctiva, sclera, cornea, anterior chamber, iris, lens, and the anterior vitreous. With the addition of certain accessories, it can also facilitate detailed evaluation of the anterior chamber angle, the macular region of the fundus, and the peripheral retina. By generating optical cross‑sections of the eye, it enables assessment of structural changes at various intraocular levels, thereby facilitating precise localization of intraocular lesions—capabilities that are difficult to achieve with other instruments.

　　The basic slit-lamp examination sequence, proceeding from the periphery inward, is as follows: eyelids—lid margin—eyelashes—lacrimal apparatus—palpebral conjunctiva—bulbar conjunctiva—conjunctival sac—corneoscleral limbus—tear film—cornea—anterior chamber—anterior chamber angle—iris—pupil—posterior chamber—lens. The examination is performed first on the right eye, then the left. During screening, each eye is examined for an average of 120 seconds; if specific findings are noted, further evaluation is conducted.

　　The following provides a detailed description of the specific inspection methods.

　　Eyelid:

　　Operator: 1. Insert the slit lamp diffuser into the optical path and examine using diffuse illumination.

　　2. The slit lamp’s illumination is set to medium;

　　3. The light source angle is 45 degrees;

　　4. The microscope magnification should be set to 10×.

　　5. During examination, instruct the patient to close their eyes;

　　6. The inspection time should be maintained between 5 and 8 seconds.

　　Eyelid margin and eyelashes:

　　Operator: 1. Insert the slit lamp diffuser into the optical path and examine using diffuse illumination;

　　2. The slit lamp’s illumination is set to medium;

　　3. The light source angle is 45 degrees;

　　4. The microscope magnification should be set to 10×.

　　5. The observation sequence is from the nasal side to the temporal side;

　　6. During the examination, instruct the patient to look straight ahead.

　　7. The inspection time should be maintained between 5 and 8 seconds.

　　Lacrimal apparatus:

　　Operator: 1. Insert the slit lamp diffuser into the optical path and examine using diffuse illumination.

　　2. The slit lamp’s illumination is set to medium;

　　3. The light source is positioned at a temporal angle of 45°.

　　4. The microscope magnification should be set to 10×.

　　5. During the examination, instruct the patient to look toward the temporal side.

　　6. The patient’s superior and inferior lacrimal puncta should be observed.

　　7. The inspection time should be maintained between 4 and 8 seconds.

　　Tear film:

　　Operator: 1. Insert the slit lamp diffuser into the optical path and examine using diffuse illumination.

　　2. The slit lamp’s illumination is set to medium;

　　3. The light source is positioned at a temporal angle of 45°.

　　4. The microscope magnification should be set to 10×.

　　5. Instruct the patient to look straight ahead;

　　6. Assess the integrity of the patient’s tear film and measure the tear film breakup time.

　　7. The inspection time should be maintained between 8 and 18 seconds.

　　Note: Observe the tear film breakup time: Instruct the patient to blink forcefully once, then start timing and continue until the tear film breaks up or the patient blinks again.

　　Conjunctiva:

　　Operator: 1. During examination, first set the slit lamp to diffuse illumination to assess the overall condition of the palpebral conjunctiva, then switch the slit lamp to slit‑beam illumination and carefully examine the area from the nasal to the temporal side one to two times (the palpebral conjunctiva must be everted by lifting the upper lid for clear visualization).

　　2. The slit lamp’s illumination is set to medium;

　　3. The light source angle is 45 degrees;

　　4. The microscope magnification should be set to 10×–16×.

　　5. When examining the superior palpebral conjunctiva, instruct the patient to look downward; examine the inferior palpebral conjunctiva.

　　Instruct the patient to look upward during the procedure.

　　6. When turning the eyelid, pay attention to your technique; if you suspect congestion, papillae, or…

　　Follicles should be observed at higher magnification;

　　7. The inspection time should be maintained between 8 and 14 seconds.

　　Cornea:

　　Operator: 1. During examination, set the slit lamp to slit illumination;

　　2. Set the slit lamp brightness to medium;

　　3. Adjust the angle and width of the slit‑lamp light source, and perform the examination in the following sequence: from the nasal side to the temporal side of the patient, and from the corneal epithelium to the cornea’s basal thickness.

　　4. The inspection time should be kept between 10 and 20 seconds.

　　5. During the examination, instruct the patient to blink periodically to assess the tear film.

　　Iris and Pupil:

　　Operator: 1. Focus the slit light onto the iris;

　　2. First, use diffuse illumination to assess the overall appearance of the iris, then narrow the slit to examine specific details.

　　2. Adjust the intensity of the slit to observe the pupil’s response to light;

　　3. The light source is positioned at a 45-degree angle to the temporal side;

　　4. The microscope magnification should be set to 10×.

　　5. During the examination, instruct the patient to look straight ahead.

　　6. Observe the patient’s iris shape and assess for pupillary constriction in response to bright light.

　　7. Time: 3–8 seconds

　　Lens:

　　Operator: 1. During examination, set the slit lamp to slit illumination;

　　2. The slit lamp’s light intensity should be adjusted to a high setting;

　　3. The angle of the slit lamp light source is 10–45 degrees;

　　4. The microscope magnification should be adjusted from low to high.

　　5. During the examination, instruct the patient to look straight ahead.

　　6. The slit width of the slit lamp is 2 mm; use a narrow light source and align it accordingly.

　　Pupillary zone: Focus the lens on the crystalline lens and scan the pupillary area to assess the lens condition.

　　7. Time: 9–15 seconds