Determine the objective of your lesson. Derive this from your school district's grade-level teaching requirements and learning standards. Students with disabilities need accommodations, but students with visual impairments should be taught the same lessons and objectives as their typically developing peers.
Begin to write your lesson plan using the format your district requires. If they do not have a specific format, use one that suits your personal preferences. Start with the methods section, and write instructions for each step as you would for any other lesson plan. Do not worry about any modifications for students at this point.
Read through your steps and then determine how you need to modify each step in order to accommodate the student who is visually impaired. If you have a step that involves moving about your classroom, you might pair the student up so that she can be assisted during this process. If there is a visual aspect to your lesson, you might enlarge the print of your display. Make a list of any accommodations at the bottom of your lesson plan.
Determine any materials you may need to complete the lesson. Include both materials for the general lesson, as well as any needed to accommodate your students. Examples might include braille books or large-print text. Make a list and add it to your lesson plan.
Read through your students' Individualized Education Plan (IEP). This document will detail any additional modifications your children with visual impairments may need on a daily basis in your classroom. An example might be to allow students to have a guide dog with them throughout the day. Look through your newly-written lesson plan and modifications to be sure you have not contradicted any of the modifications outlined in the IEP.
Teach this lesson to your class, and then make notes of ways you might improve it for future teaching.